CA2172651C

CA2172651C - Modem communications interoperability with services equipped to provide calling party identity delivery with call waiting

Info

Publication number: CA2172651C
Application number: CA002172651A
Authority: CA
Inventors: Lujing Cai; Nuri Ruhi Dagdeviren
Original assignee: AT&T IPM Corp
Current assignee: AT&T Corp
Priority date: 1995-06-01
Filing date: 1996-03-26
Publication date: 1999-07-13
Anticipated expiration: 2016-03-26
Also published as: CA2172651A1; US5550908A

Abstract

Techniques are disclosed for providing interoperability between a first modem and a calling identity delivery on call waiting (CIDCW) service. According to an embodiment disclosed herein, a first modem is coupled to an alerting signal receiver and a communications re-establishment device. The alerting signal receiver receives an alerting signal generated in response to an incoming call from a third party line if the first modem is communicating with a second modem. The communications re-establishment devicereestablishes communications between the first modem and the second modem after the alerting signal receiver receives an alerting signal. The first modem is equipped to receive the alerting signal and reestablish communications with the second modem independent of the specific capabilities of the second modem, so that these techniques can be utilized in conjunction with a second modem not constructed in accordance with the embodiments disclosed herein.

Description

` 2172651 .
Modem Commnnications Interoperabilib with Ser~ices Equipped to Provide C~llin~ Party Id~ Delivery with Call Waiting B~.~k~ 1 of ~e Imenffon s Descri~ffon of Prior Art Caller Identity Delivery on Call Waiting (CIDCW) is an optional service pl~,~n~
offered to te LP~Ph~)t1e SUbS~`r;1~rS by some Local Fy~h~nge C~riers (LECs) overcon~/enl;- n~l tip/ring lines. The seNice is useful in situ~tiQI~Q- where telephonic comm-lnisfltiol-Q are in progress between a first telephonic device and a second telephonic 0 device, and a third party directs an incoming call to the first telephonic device. If this first telephonic device is conmPc~d to a tip/ring line that is activated to impLPmPnt the CIDCW
service, the LEC sends an alerting signal to the first telephonic device to alert the telephone s~l~sçriber as to the exiQtence of an ;nco~ ng call from a third party. If the first ~Pleph~nic device responds to the alerting signal with an acknowhPdgJn~nt signal, then the 15 LEC sends an identity signal (also referred to as a CID signal) over the tip/ring line to the first tPlephollic device. The identity signal is indicative of the identity of the third party. In the present e~mple the alerting signal and the identity signal together compriQe a first alerting signal sequence. If the third party call is not answered within approYim~tely ten ~Q~OndvQ after the termin~tion of the first alerting signal sequence, the LEC sends a second 20 signal alerting sequence to the first telephonic device. This second alerting se~llJe~r~
includes an alerting signal and, provided that the first telephonic device responds to the alerting signal with an acknowledgment signal, the second alerting sequenr,e also includes an identity signal.. Although the present eY~mplP describes an alerting signal se(luenGe that includes both an alerting signal and an identity signal, it is to be under.Qtood that an 25 alerting signal s~ucnce may include any desired combin~tion of alerting signals and/or identity signals.
The CIDCW service differs from co~ nl iQn~l Call Waidng se. ~i~es in that CIDCW d~L~,.s the identity signal immedi~tply after the alerting signal is dcli~e.ed. This process provides t~lephone su~ with con~enience of identifying i,.-polt~nt 30 incu~n;ng tclephQ.-r calls while an e~i~ting telephone call is already in progress. In this - 2 ~172651 Fpl-rl~-f s"~ are provided with infotm~ti~n helpful in d~id;~g ./h.,~.,~
or not to switch to the new, incc~ g telephone call from an e~ g telephone call.CID(~W may be conQi~lp~red an enhAn~en.en~ of con~ ;onAl caller ident;r~;on (caller ID) services, which deliver informAtion pe.~i~ g to the identity of the calIing party only s when the called party is in an on-hook state.
Technologies in voice band data communi~Ati~)n~ have matured to the point that modem usage is now fairly commonplace. For k~ ple, modems enable rPsid~PncP-based pe ~sonAl computing devices to access large mAinfrA,n~e coln~ at central bu~ess locations over con~e.. ~i()nAl PSTN (public switched telP.phone nelw(,l~) telephone lines, 10 and to access various on-line dAtAbAQP services to lt;l,ie~e various types of inf~rmAtion These appli~At;on.c often utilize a telephone col-nfclion for a rather lengthy period of time.
It is not at all ImllQuAl for a telephone line to be in use for hours at a time while a tPleph~ne sllb~ribe~ is performing on-line datqb~qQP, seal~ches. If a third party ~ " to call the tPlPphonP sllh~scriber while the su~s~riber is already en ~ed in modem-to-rnodpm lS co~----ui-ir~ n.c, the inco~;n~ caller will receive a frustrAtin~ busy signal, with no indication as to why the called party's line is busy.
The CIDCW service provides a potential sol~ltion to the above problem.
Unfortunately, e~icting modem products and appli~qtionc (modem software) are notcompqtible with the CIDCW service. Upon receipt of an incoming call from a third party, 20 the CIDCW service sends an alerting sequence to the first telpphQ~ic device, which effectively blocks all modem-to-modem communications for a block-out period lasting on the order of a few secon~c. ~IodPmc respond to such a block-out period by d;ccol necl;n~g from the tip/ring line, effectively tel.~-inat;ng modem-to-modem cQmm~ ;calion~ even after the CIDC~r ill~lluption has ended. The maximum block-out period is 2.6 seconds if 2s the first tPlP.phonic device acknowledges receipt of the alerting signal with an acknowlPd~men~ signal, and 1.17 seconds if the first tPkPphonic device does not acknowledge receipt of the alerdng signal with an acknowlP~gment signal. In either case, this block-out period would be of a du~tion ~--rr~iP~-t to cause t,- ,.. il~a~;on Of modem-to-modem co..~ vuica~ionc unless special pleca-ll;o~c are taken, as will be d~Pscrihed in 30 greater detail ~,~in~r.

After modem-to-modem cGm~ ic~tionc have been in~,l~ted due to the oc~iul~e. ce of one or more CIDCW alerting signal sc~luences, the modemic ntt~P-mpt a .inin~ p~vce.lule to reestablish commnnir~tio~c. Such ~ din~lg procedures typically require at least ten ~oecon~lc. Due to the fact that a second CIDCW alerting sequence may be sent out al)p~o,~ tely 10 seconds after termin~tiol- of the first sequence (as described above), this second CIDCW alerting sequence will likely interfere with a modem-to-modem l~t-~ining procedure already in progress. Note that the perform~nce of a modem-to-modem retrain procedure requires more than 10 seconds, and that retrain cQmmPn~Rs after the first CIDCW alerting sequence has termin~tPd, i.e., after the FSK data block has been received at the mod~pm ~'onsequ~pntly~ the second CIDCW alerting s~uenr,e proves to be de,,tlu~;live in that it arrives in the middle of retrain eco~e,~.
What is needed is a technique for providing i"le~pe,~bility belween a first modem and a CIDCW service. Such a lechlli~ue should enable the first modem to receive a caller ide,~ (CID) signal without dropping an eYicting connection belween the first modem and a remote modem. The first modem should be equipped to implement this technique independent of the specific capabilities of the remote modem, so that these techniques can be utilized in a system that may include an existing modem product not constructed in acco~lce with the embodim~ntc disclosed herein.
Brief Descrip~on of the D. ~
FIG. 1 ic a hardwd~ block diagram showing a system constructed in accor~ce with an embodiment ~ic~losed herein;
FIG. 2 sets forth an ill~ live si~n~ling procedure used in conjunction with an e~icting caller identity delivery on call waiting (CII)CW) service;
PIGs. ~ and 4 are software flowcl~ s ill~ ing a first set of operational 2s ~ce ~"e~-r~s for providing i,~ opel~bility between a modem and a caller identity delivery on call ~ ing (CIDCW) service; and FIGs. S and 6 are software flowcharts illustrating a second set of oper~tion~l ~luc n~xs for providing in~ bility belween a modem and a caller identity deL~c,~ on call waiting (CIDCW) service.

Summarv of the Invention Teçhni~luçs are ~ic~losed for providing ir,t~ pel~bility bet~ ee.~ a first modçm and a caUer identity delivery on call waidng (CIDCW) service. Accol~du~g to an embodiment ~i~cloæd herein, the first modem is couplP-d to an alerting signal lece;ve~ and a S coU~ n~ ;on-C re-est~hli.chmç~t device. The alerting signal ~ece;ve, enabled when the fir.ct modem is commu.-ic 3t;,-g with a second modem, ~ec~ s an alerting signal s~ucnce ~ne~ted in response to an inco,nh~g call from a third party line. The communi~tion.c re-establi.chmçnt device reestablishes communi~tionc between the first and second nlodçms after the alerting signal receiver l~;ce;~es an alerting signal .~equenGe The alerting signal ~ue.n~e consis~ of any comhin~tion of alerting signals and identity signals. The identity signal in~ltldes info~tinn specifying the identity of the third party line. The first modem is equ;ppe~ to receive the alerting signal ~cequenGe and to re-establish an çYictin~
conl-ec~ n to the second modem independent of the specific c~p~hilities of the second ml)de.m In this ~ er, the first modem may be utilized in conjunction with a second modem not constructed in accordance with the embodim~nts ~icclosed herein.
Detailed D~c, ;,vt;on of the Invention The tçchnie~l p~r~mpter~c of caller identity delivery on call waiting (CIDCW) are set forth in Bellcore Teçhni~al Refelence TR-NWT-000575, CLASS Feature: Calling Identity Delivery on Call Waiting, FSD 01-02-1090, Issue 1 (Bellcore, October 1992), and Bellcore Technir.~l Reference TR-NW r-000030, Voiceband Data T. ~n.~ i.csion ~nt~rface ~çnP.ric Re.luile.~.e.ntc, Issue 3 (Bellcore, April 1992), both of which are e,~,lessly incorporated by lt;fe.~ ce herein.
According to an embodiment di~losed herein, an eYi.cting CIDCW service opel~k;s in conju".ilion with the ha~ . d~ conf~ ation of FIG. 1. p~.rc-~ ;np now to FIG.
2S 1, a first telephoni~ device 100 is coupled to a first end of a first tip/ring line 106. An e~t~P.ncion t~PlephonP. set 105 is also couplçd to the first end of first tip/ring line 106 in parallel with first telephonic device 100. Although eYtçnciQn telephonP- set 105 could be virtually any type of telephonic device equipped to implemp-nt voice communil~tionc~ in the eY~nple of FIG. 1, eYtPnSiQn telephone 105 is a POTS telephone (plain old telephone set). FYt~Pn~ion telephonP, 105 generally remains on-hook while modem-to-modem corn~ iG~1;0l~c are in progress.
The second end of first tip/ring line 106 is connected to a stored program 25 control switch 110 (SPCS) at a central switching office 108. In the present eY~mple, it is 5 ~ d that the t*leph-)ne customer using dp/ring line 106 is a CIDCW s-~bs~-~ibPr.
Th~,.Gfole, SPCS 110 is equipped to implement the CIDCW service over tip/ring line 106.
In order to advantageously utilize the CIDCW service, first telephonic device 100 is equipped with an alerting signal çGcGi~e. 102, a caller identity inforrn~tion lGce;~ef 104, and a DTMF (dual-tone, multi-frequency) tone gelle.~tor 103. The alerting signal lGcc.ve 102 is responsive to alerting signals tr~n~mittPd by the SPCS over first tip/ring line 106 to produce a humanly ~i~ce- ~ le in~ ation signifying the receipt of an alerting signal. The caller identity information l-,cei~,ef 104 is lGspol~ive to caller identity inform~tion to produce a humanly ~i~ce- ..iblP indi~ntion specifying the identity of a calling party. A
suitable receiver for use as caller identity inform~ion receiver 104 is known to those skilled in the art as a Bell 202 receiver. The DTMF tone generator 103 generates an acknowledgment signal in response to the receipt of an alerting signal by alerting signal ~ei~ 102.
A first end of a second tip/ring line 112 is connPcted to a switch 122 in central switching office 108, and a second end of second tip/ring line 112 is co~ ecl~d to second 20 tPIephonic device 114. A first end of a third tip/ring line 116 is COI nP~iled to a switch 120 in central switching office 108, and a second end of third tip/ring line 116 is connPcle-d to a third t~leph~ ~ic device 118. Central Sn/ilching office 108 is equipped to selectively control and/or inte~om~ switch 120, switch 122, and SPCS 110. Two s~/ilelleS, switch 120 and switch 122, are shown in FIG. for illustrative purposes, it being ~nrlprstood that 2s the embo~;P~ cctosecl herein cont*mpl~te the presence of a multirlicity of s., it~hes in routing some of the catts involved.
In the present example, first and second telephonic devices 100, 114, lespe~vely, clll tel~phone equirmpnt adapted to imphPmpnt modem commllnic~tion~ First telephonic device 100 includes a modem 124 coupled to first tip/ring line 106. Modem 124 is controlled by a modem processor 126 equipped to execute modem soflw~. This 6 21726~1 sorlwal~, sometimP,s referred to as a modem ~rplir,D~ti~-n, controls the oper~ti~n of modem 124, for e~mplP., through the use of convç~;on~l AT comm~n~c well-known to thoseskilled in the ar~ Modem 124 may opdonally be upgraded to selecdvely apply switch hook flashes to first dp/dng line 106, and/or to detect the off-hook status of an eYten~ion 5 t~Plerhon-P, device co~ P~ to tip/dng line, such as e~ n~;on ~PIephn~P- set 105. ~lthollgh mQ~Pm 124 need not he equipped to pe.r,llll error co,~,tion leC~ 1eS, the l.Dntlli~ of CIDCW events is greatly fac~ tP,d if mod~pm 124 and modem 144 are co.. ~ni~ .g using an error correcdon protocol such as V.42.
A user inte~ ce 128 in~ludes one or more user interf~e devices such as a keypad,push-button s~,vitches, a computer keyboard, and/or a video display device. User int~ r,e 128 is coupled to modem processor 126.
Second telepllonic device 1 14 may have a hardware structure similar to that of first telephonic device 100, but there is no lequil~menl that second telephonic device 114 include hardware ~L,u ilurl,s idPnti~l to those of first t~PlPphonic device 100, so long as both first and second telephonic devices 100, 114, respectively, include modem.~ 124, 144, .~sl e~l;vely. In the present es~mple~ second telephonic device 114 includes modem 144, modem processor 146, opdonal user interf~cel48~ opdonal DTMF tone genPr~tor 154,opdonal alerting signal receiver 150, and optional caller idendty infonn~tion ~ceivel 152.
~ this lll&nl e~, first tel~P.phonic device 100 p~ vides illt~perability with eYi.ctin~ CIDCW
services, i l~,spe~,tive of wllc;lllcr or not second telephonic device 114 provides such int~upe~bility.
Alerting signal ~;~" 102 and caller idendty ;~rO~ ~ tit~n l~ce;~e 104 are shown as being fully int~ d within first telephonic device 100. However, the alerting signal l~.CeiV~ 102 and/or caller identity 1t;cei-erlO4 could be external to first telephonic device 2s 100, so long æ the alerting signal receiver 102 and the caller identity inform~tion l~ cr 104 are both c,r led to first tip/ring line 106 through the use of a filtering and i~ol~tion device such as a directionql coupler. The direction~l coupler serves the p~u~,ose of solqtiTlg modem signals l~ncln;ll~d by first modem 124 from the alerting signal l~,C~
102 and the caller identity informq-tion ~c~ " 104. Although modem 124, D'rMF tone 30 ~ -n~ or 103, and modem pl~essor 126 are shown æ discrete blocks, it is to be lmderst~od that these block~s may actually l~,pl.,sent a single integrated device that inrl~ldes a modem, a tone gcne.ator, and a plocessor.
Third t~ .ph~ device 118 l~,lese,lls any device capable of est~hlichi~ and pc.rol,~ g co~ r~t;on.c over third tip/ring line 116, and, theleÇol~;, third tPlephonic S device could, but need not, include a modem. In the present e~qmrlP, third telephQnir device 118 is aPOTS telephone (plain old telPpho~P- set).
The CIDCW service operates as follows. Assume that modem 124 to-modpm 144 co.~ c~l;on.c are plesenlly taking place belween first telepht)nic device 100 and second tplephonic device 114 via first tip/ring line 106, SPCS 110, switch 122, and second 10 tip/ring line 112. Subsequent to the establishmP~t of modem 124-to-modem 144 comm-micq~tions, but before such communications are termin-q-ted the central ~,vi~l ing office 108 lc;ceives an incoming call from third telephonic device 118 directed to first telephonic device 100. In response to this third-party hlco,nhlg call from third telephonic device 118, SPCS 110 alerts first telephonic device 100 as to the e~istenr,e of the s i~co~;ng call by sen~ling an audible alerting signal in the form of a Subsc~ ;her Alerting Signal (SAS) to first telpphonic device 100. Next, the SPCS 110 sends first telephonic device 100 another alerting signal termed the CllstomPr premises equirmPnt Alerting Signal (CAS). In ,~sponse to the det~-ction of the CAS alerting signal, the DTMF tone gene.ator 103 of first telephonic device 100 tr~qnsmitc an acknowlP-dgmPnt (ACK) to 20 SPCS 110. The ACK signal, in the form of a DTMF tone, in;,~ .u;~ SPCS 110 to cQl..-..f nce tr~qnsmi~sion of FSK data that incl~ldç calling party identity informq,tion, also referred to as CID informq~tion~ The SAS signal, CAS signal, and FSK data, takentogether, compri.ce a first alerting signal sequence.
The çhq~teri.cti(~ of the SAS, CAS, and ACK signals are shown in ~IG. 2. The 2s dvr.qtion of th-e SAS signal 200 sent by SPCS 110 (FIG. 1) is approximvtely 250 to 400 milli.c~cQ~c, the duration of the CAS signal 202 is apploAilllately 80-85 milli~econdc, and the duration of the FSK data 206 that includes CID information is less than one second.
The CAS signal 202 is not sent out imme~iqtply after ce..ccqtion of the SAS signal 200, nor are the FSK data 206 sent out imme~i~qtely after cessation of ~e CAS signal 202; these 30 signals are sep~at~d by brief time intervals such that the total elapsed time from ~e :- 21726~1 be~,jnnil~g of the SAS signal 200 to the be.~ nil~ of the FSK data 206 is from ap~ ly 535 milli.~con~s to 1170 rnilli.~P,col~.C The ACK signal 208 is sent out by ~Plpph~nic device 100 in response to the receipt of a CAS signal 202, and the dU~tiQn of the ACK signal 208 is appr~ t~ly 60 milli.~con~ Ihe total time period during which S mo~em-to-modem com...~ h~;on.~ are i~ .~ted ~t~een first and second telepho~
devices 100, 114 (FIG. l)"~spe.;lively, is of the order of no greater than 2.6 s~CQndc.
In order to p-evellt a remote party at second te~ephQni~- device 114 from hearing the SAS signal 200, the CAS signal 202, tbe ACK signal 208, and the FSK data 206, SPCS 110 ~ po-~ily b!ocks all communi~ti()~ belween first t~lephonic device 100 and 10 second telephonic device 114 until the ~n.~mi.~siQn of FSK data 206. As previously stated, for a convel-l;on~l CIDCW service. the entire block-out period lasts for no longer than 2.6 secon~s. However, note that SPCS 110 (FIG. 1) will not transmit FSK data 206 unless the SPCS 110 receives an ACK signal 208. In the case where SPCS 110 does not receive an ACK signal 208 from first teleph~ nic device 100, the SPCS 110 .e~w~s the cQmmnnic~ti-)ns path ~lwt;en first and second teko.ph-)nic devices 100, 114, ~spec!;vely, shortly after termin~tiol~ of the CAS signal 202, leading to a much shorter block-out period of less than 1. 17 sPcQn~
Based upon inform~tion inclllded in the FSK data 206 block and received by caller identity inform~ti~ eceiver 104 (FIG. 1), the CIDCW cll~tQmer (i.e., ~e user) using first telephonic device 100 may choose to answer the third-party inco~l;n~ call by, for example, fl~hing the switch hook of first telephonic device 100. However, instead of answering the third-par~y incQmirlg call, the CIDCW cust~mer may prefer to ignore this call. Th~leîol~;, user interf~^e 128 issues a prompt, ~ue~ g the user to take certain action, such as pressing a key or fl~hing the telephone switch hook, if it is desired to accept the third-2s party incoluing telephonp call. ~ the user wishes to accept the call, app.l,pliate inÇ-. ,..~tiQn, such as a key press, may be entered into user i~tp~rf~oe 128 or, ~ . "A~ ,ly, the user may flash the switch hook of tPIep!-ol-ic device 100.
An aler~ng signal s~nce may include any combination of a CAS signal 202, an SAS signal 200, and FSK data 206. After pe,~eivillg a 11IIIU~I1Y ~;~,. ..;hle i.~ Al;~n 30 gF ne~t~ ~ by the aler~;ng signal le~;ver 102 in ~ponse to receipt of an alerting signal ~uence, the user may fail to flash the switch hook or fail to enter other approp,iate input into user int~Prf~se 128. In the present eY~mplP, the alerting signal s~lue~ce includps an SAS signal 200 followed by a CAS signal 202, as shown in FIG. 2. If the inSG..~i~ call from the third tel~Pphonic device 118 is still active, i.e., the third party has not retumed the s third tPlephonic device 118 to an on-hook condition, then the SPCS 110 (FIG. 1) sends a second alerting signal sequence to the first telephonic device 1 00 app~ ;.n~tely 10 secon~c after the first alerting signal sequence is sent. In the present eY~mplP, this second alerting signal sequence incl~ldes an SAS signal 200, although the second alerdng signal could include an SAS signal 200 in addition to a CAS signal 202, and, in either case, this 0 second alerdng signal sequenrR could, but need not, include FSK data 206.
Upon receipt of an in~oming caU from third tel~Pphonic device 118 and the re~llffn~
acdvadon of the CIDCW service by SPCS 110, modem 124 -to- modem 144 c~ .n..~ k~;onc b~tween frst and second t~l~ph~nic devices 100, 114, l.,~ectively, will be int~ lupted for about 2.6 seco~ds. The effect of a 2.6-æcond hl~llu~tion on modem 124 -to- modem 144 communications is as follows. For conventional modem operadon, con~ t carrier energy on the dp/ring line 106 (FIG. 1) is necesc~ry to m~int~in a stable modem-to-modem commnnirationc Iink. If this co~dition is not met, the modem tends to n~i~conn~", i.e., to return to an on-hook con~lition shor~y after loss of carrier.
The dme duradon for which modem 124 will remain off-hook and con~ ted to 20 tip/ring line 106 (F;IG. 1) during a carrier interrupdon is determined by a software ~ppli~?tion eY~ecu~P-d by modem processor 126. Modem 124, as well as many plese.llly-eYi.cti~ modems, include this software application in the form of a register known as the S10 leg~r. The nllmPri~l value loaded into the S10 register de~l,ni,.cs the amount of time forwhich.the modem will remain off-hook during a modem carrier ihltelluplion 2s before d~ n takes place. A default value less than or equal to 2 seconl1c is typically loaded into the S10 register.
If a mocl~Pm carrier is in~lupled for a period of dme greater than about 1.5 secon~s, the modems must pelrollll a ful} retrain procedure in order to leco~,r modem-to-modem communications. Typical retrain ploce.lules require about seconds or more to 30 reestablish communic~ion~. It should be emph~ci7~d that, during the le~ ;n~ proceJv~e, - lo 2172651 any signals on dp/ring line 106 (FIG. 1) that are not a part of the le!~i.;n;ng plO~edUle will cause retrain failure. Likewise, any ~ cor~l;nu;l;~s or illt~,~luplions along a path in-~lu-~ g first tip/dng line 106, SPCS 110, switch 122, and second dp/ring line 112 will also cause retrain failure. If retrain failure occurs, most eYicting modems will l-nCQn~itinn~lly S disconnc.,l from the tip/ring line without a~ ting any ~Idition~l retrain procedures.
In order to provide illt~"~opelability ~n a first modem and a CIDCW service, techniques are required for receiving CID (caller idendty) infQrm~tion without dloppil g an e~i~ting connection bel~e- the first modem and a remote mod~Pm The first modem should be equipped to implP.mPnt these tPchniquP,s independP,nt of the speçific capabilides 0 of the remote modem, so that these teçhniq~les can be utilized in a system that may include an e~ tin~ modem product not con.,hu~;~d in acco~ ce with the embo-1imPnt.~ di~losP~d herein.
FIGs. 3 and 4 are software flo~. ch&-~ setdng forth a first set of operational ~lue-n~'P,S for providing inlelope~bility ~l~neen a modem and a calling identity delivery 15 on call waidng (CIDCW) service according to a first embodiment ~isclosed herein. The operational sequence of FIG. 3 is performed by first telephonic device 100 (FIG. 1), and the operadonal sequence of PIG. 4 is performed by second telephonic device 114 (FIG. 1).
Flrst te~P.ph~)nic device 100 may be concept~ i7P,d as ~ sentin~ a local modem-cyuipped device, whereas second t~PlPphQnic device 114 may be col ce~ li7~d as 20 leplese..~ g a remote modem-equipped device.
The local modem-equipped device incl~ Ps enh~nced software for eYecuti~ the opp~t;t n~l sequence of FIG. 3, ~.heleas the remote modem-equipped device includcs e~h~nced sor~ u~; for e,~vcul;ng the oper~tion~l se lucn~ of FIG. 4. In practice, a modem col~l.ucled in accolddnce with an embo~im-P,nt ~i~losed herein would be equipped with 2s software for t;~c.,~ the opvMffon~l se.lucnces of FIG. 3 as well as those of FIG. 4, so as to enable a given modem to function as a local modem in some ~ l;on.c and as a remote modem in other ~itu~tio~ For example, a third paTty call dile~i~d to the user of a given modem would render that modem the local modem. By cont~t a third party call directed to the user of a second modem to which the given modem is plt;~el-lly 30 comm,,,-i~ g would render the given modem the remote modem. The operflti .
enee of FIG. 4, performed by the remote modem-equipped device, illllstr~tes the ~l~am~er in which the enh~n~e.d software of the remote modem-equipped device interacts with the enh~nced software of FIG. 3.
The operational sequence of FIG. 3 comm~Pnces at block 301 where a local modem 124- to - remote modem 144 (l;IG. 1) communic~tions link is established. At block 303, a stable modem-to-modem communic~tions link is in progress. Next, first telP.ph~ nie device 100 (FIG. 1) detects an alerting signal sequence (E;IG. 3, block 305). This det~Pctinn may be pelrol,ned such that only a portion of an alerting signal sequence is detect~,d or, ~ltPrnatively, the te1Pphor-ic device 100 may test for the eYi.ctpnre of an entire alerting signal ~u.,-lce at this time. A test is performed at block 307 to ~ele~ mine whether or not this is the first alerting signal to be detected in a given alerting signal sequence. For eY~mple~ an alerting signal sequence may consist of an SAS 200 signal followed by a CAS
202 signal (PIG. 2). In this case, the first alerting signal is the SAS 200 signal. The ~ffirm~tive branch from block 307 (FIG. 3) leads to block 309, whereas the neg&tive lS branch from block 307 leads to block 321.
At block 309, the DTMF tone generator 103`(FIG. 1) does not send an ACK
(acknowledgment signal) (FIG. 2, 208) to SPCS (FIG. 1, 110). SPCS 110 restores the signal path between local modem 124 and remote modem 144. This path was broken by the SPCS 110 dudng the time that the SPCS sent the first alerting signal to first telephonic device 100. Due to the fact that the signal path was inte,-upled for a relatively bdef period of time, modem-to-modem commnni~tions now ~ltom~ti~lly resume, and this ,~suml)lion occurs without the eYPCution of any modem leL,ainil g sequence (block 313).
Local modem processor 126 sends a CIDCW_REQ message to the remote modem plocessor 146 signifying the eri.~tenee of a call waidng event (block 315). The local 2s modem processor 126 disables a carrier-drop dmer. This dmer is erre.;li~,ely provided in the form of the previously-described S10 register. In the present ex~mple, the value of ~e S10 l~gis~r is set to an app,opliate value (i.e., 255), such that the local modem 124 will not dicco~ cl for an indefinit~ period of dme in the ~bsence of a modem carrier signal (block 317). At block 319, the local modem processor 126 r~cei-/es an IND_ACK
m~$~e from remote processor 146. IND_ACK is a mess~~e sent out by a ~ 12 2172651 ,icrvplocessor that is indicative of the receipt of an ACK (~hlvnrled~nPnt) signal by tbat mic~vl"oce~sor. After perform~nr,P~ of the operations at block 319, program control loops back to block 303.
The negative branch from block 307 leads to block 321 where the first telPphonirdevice 100 (PIG. 1) responds by sen~ling an ACK signal to-the SPCS 110. The f~rst tPlpphonic device 100 then l~ce;~les FSK data from the SPCS (block 323), and the local mQd~Pm p,ucessor 126 plvnlpts the user of first trlephol~ic device 100 with caller d~Pntifir~ti~ m inro~m~;c n specirying the identiq of the third-party caller.
At block 327, the user must decide whether or not to accept the inco~ g third-parq calL If the user decides to accept the call, program control a.lv~ ces to block 337 where first telPphonir, device 100 applies a switch hook flash to the first tip/ring line 106.
At block 339, the user of first telephonic device 100 is engaged in telephonic communiC~tiol~ with the third-party caller, and, at block 341, t~P-lepho~ic communic~tions with the third-party caller have been completPd The first ~PhPphonic device 100 applies a switch hook flash to the first tip/ring line 106 (block 343). Program control then jumps to block 329 where the local modem 124 sends a retrain signal to the remote modem 144 and starts a retrain process. Note that the negative branch from block 327 leads directly to block 329 and, in this case, the steps of blocks 337-343 are not performed.
After the opP,r~tionC of block 329 are performed the program a.l~dnces to block 331 where the local modem pr~cessor 126 l~;CO~/elS the carrier-d~op di~col~nP-;l timer.
This r~...cl;~ n may be ~cco~pli~hed by setting the pl~,~/iuusly-de~ribed S10 leg~t~,r to an appl~,p,;dt~ value. Next (block 333), the local mod~Pm ~l~cessol 126 sends a CIDCW_END ..~e5'~,~ to the remote modem pr~cessor 146. The CIDCW_END mes~gP
is a mp-ssa~ sent out by a l-.iclu~,lucessor indicative of the ~e~ .nin~1;on of a call waiting 25 event by t~PlPphonic eq~lipment coupled to that mic~processor. The local mod~Pm pl~cessor 126 then lece;ves (at block 335) an END-ACK me~Q~ge from the remote modem plocessor 146. The END_ACK mesQ~ge is sent out by a micl~,prucessor in response to that miclopl~cessor having succe~rully received a CIDCW_END meQQs~P
At this point, the program loops back to block 303.

.
With respect to the procedure of FIG. 3, at the time that an incoming call from the third party arrives at the SPCS 110, the comm~mi~tions path belween the local modenl 124 and the remote, modem 144 is ~Illpol~ily i.l~llup~d. Then, the alerting s~l~,en~ is inserted by the SPCS and sent to the first telephonic device 100 where the alerting 5 s~u~nCe iS easily de~ected To avoid retrain failure, the local modem 124 is p~ ~mlled to effectively ignore this alerting sequence. The local modem does not return any acknowled~ment signal which would prevent data ~ ,..i.c~ion from taking place. As a result, the con~ J~-ic~ti-)n.c path belween local and remote modems is ~stolcd shor~y thereafter, within a time period that is of sufficjently short duration for the modem-to-10 modem connP,ction to be .eco~eled without retrain. Therefore, comm~-ni~tions bt;l~n modem ploce~co.~ 126 and 146 is re-established well before the second alerting signal sequence arrives. In this manner, a CIDCW_REQ mesc~ge (or an equivalent mess~ç
in~ic~tive as to the eYi~tçnce of a CIDCW call waiting event) can be sent from tne local mod~Pm ~locescor 126 to the remote modem processor, effectively informing the remote lS modem processor 146 to be prepared for a CIDCW (call waiting) event. The carrier-drop-~iCcon~e~l timer in the local modem 124 is then set to an effecdve value of infinity by loading the S10 register with a value of 255 (~plesenli~.g infinity in the present case) after the alerting signal se~uence is received from the SPCS 110.
Refer now to FIG. 4, which sets forth the sequence of operadons to be performed 20 by second t~lephonic device 114. Note that these operadons are performed h~t~ livel~
vith the s~uel~ce of ope~tions implPmPntPd by first tehPph()nic device 100 ac de~c-crihed above in conlucl;ol~ with FIG. 3. At block 401 (FIG. 4), a local modem 124 - to - remote modPm 144 (FIG. 1) communir~tions link ic established. Modem-to-modem communic~tion.c may take place at block 403 (FIG. 4), where a stable modem-to-modem 25 c~ mm~mic~tionc link exists between the local modem and the remote modem. At block 405, co-...u~-ica~ion.c to and from the remote modem 144 (FIG. l) are blocked out by the SPCS 110 during a CIDCW call waiting event. This CIDCW call waiting event occurswhen central ~ilching office 108 receives an incoming call from third tPlephoni~ device 118 directed to the pa ty using first telephonic device 100.

At block 407, a test is pe-rformed to a~tain whether or not the c~m~ cations block-out of block 405 is the first communic~ti- mC block-out to have oc~ lcd within the last n seconds. n is sekPct~d to be greater than or equal to the m~;.n...n d...~;nn of a CIDCW alerting signal ~ e~ce which, in the present case, is about 10 ~QI~S, The S ~ffirmfltive branch from block 407 leads to block 409, and the l~g~-v branch from block 407 leads to Uock 421.
At block 409, the SPCS 110 restores the co~n~unie~ on.c path ~t~ æn the local and remote modems within a period of time less than m seconds, .. hclc;in m l~p,~,l~ a real number of a sllffi~;ently short du~tion such that the local and remote modems do not have to perform a retrain to reestablish communications. The remote modem to local modem COI~mUniC~tionc link flutom~ti~ y resumes without retrain (block 411). Theremote modem processor 146 receives a CIDCW_REQ mess~e (block 413) in~ic ~ , of a request to prepare for a CII)CW call waiting event. The remote modem processor sets the carrier-discQ~ cl drop timer in the modem by sefflng the S10 register to an ap~l~opliate value such as 255, where 255 l~,pl.,sc.l~ a value of infinity (block 415). The remote modem plocessor then sends an IND_ACK mesc~ to the local modem pl~ccssor 126 (block 417) acknowledging receipt of the CIDCW_REQ mess~e of block 413, and program control loops back to block 403.
The l~egati.~, branch from block 407 leads to block 421 where the remote modem 144 holds the first tip/ring line 106 and waits until a modem carrier is no longer l.,ce;~,~,d from the local modem, i.e., until the modem carrier d~ops. Once the carrier drops, the remote modem processor starts a "wait timer". At block 425, a test is performed to ~e,~in whether or not the wait dmer has dmed out. If the wait dmer hæ dmed out, the remote modem 144 discQnnecls from the dp/ring line 106, effecdvely tPrmin~tirlg 2s communiC~t;~n.c ~ the wait tdmer has not yet timed out, the program ad.~ances to block 429 where a test is pelr~"...ed to as~l~in ~hcll.cr or not the remote modem hæ received a retrain signal. If not, the program loops back to block 425. ~ so, the p~Gg~ull ad~ ces to block 431, where the remote modem starts p~ . rO, .n;n~ a retrain procedure. The remote modem 30 ~,ocessor ,~ ,s a CIDCW'_END rnP.~cap~,P from the local modem ~,~ccssor i~ul ie~t;~ of ` lS 2172651 the end of a CIDCW call waiting event. The remote modem pr~cessor sets the car~ier drop timer (i.e., the S10 register) to a nomin~l value (block 435). Next, the remote modem processor sends an END_ACK me~ca~e to the local modem processor indic?ltin~ that the remote modem processor ~l~no~.ledges the end of a CIDCW call waiting event (block s 419). The program then loops back to block 403.
Upon rccei~ing the CIDCW_REQ me.cc~e at block 413, the remote modem P1GPd1eS for a call waiting event by sefflng the S I 0 register to a value of 255, errec~ Gly diS~li~ the modem carrier-drop-~licconnPct timer. This allows the remote modem to endure the longer interruption in commllnic~tiollc accoci~ted with the second CIDCW
10 alerting signal sequence. Therefore, even though the modem connection is ~iccon~in~Jed during the comml~ni~tiol~s block-out, the remote modem will remain in the off-hook state, and remain holding the tip/ring line.
In conjunction with the ope~tionc of FIG. 4, caller identific~tinn (CII)CW) inform~ti- n is lGceived as follows. Ten æconds after the first alerting signal s~uGnce is ent to first telephollic device 100 by central ~v,/ilching office 108, the SPCS 110 sends a second alerting signal sequence. In the present case, this second alerting signal se~luence includes a full FSK data tr~ncmi~csion setting for~ information pe.~hlhlg to the identity of the calling third party. The FSK data tr~n.cmi.c.cion occurs because the third party call was not ar~.cl~d immedi~tely after the first alerting signal sequence was received at first 20 t~lephomc device 100. At the time that the second alerting signal se4uence is lece;ved by first t~lephQnic device 100, the first telephonic device returns an ACK signal to the central Sn~ilching office. Also at this time, the caller identity information receiver 104 of first telephonic device 100 is enabled for receiving FSK data. Upon receipt of this FSK data, the user is p~lllpled with caller identity (CID) information specifying the identity of the 2s third-party caller.
The CID h-fo. "~tion received by caller identily illro~ tinn l~;ce;~,e. 104 enables the user of t~l~.phQnic device 100 to make an informed dec ~ n as to whether or not to answer the il~o~;n~ third-party call. Lf the user choose to do so, the local modem 124 flashes the switch hook to instruct central ~wi~hing office 108 to conne.il to the first 30 dp/ring line 106 to the third-party incQming telephone call. Next, the user intprf~ce 128 , ilY~hu~lS the user of first telephonic device 100 to pick up ~ t~ ion t~lephrne set 105 to e~t~lish co~ vniC~t;o~e with the third-party caller. When the call is over and the user of first tçlP.rhnnic device 100 hangs up c- tçnci~ n t~l~phone 105, the local modem 124 flashes the switch hook again to instruct the central switching office 108 to couple first tip/ring 5 line 106 with second telephonic device 114.
If the user of first telephonic device lO0 does not intend to answer the third-party i,~co,l,ing call, or if the third party inco"~ing call is lost for some rewn, a full retrain procedure is initi~ted imme~i~tely by the local modçm~ or by the modem that would have restored modem-to-modem communi(~t;on~ upon termin~tinn of the third-party calL
10 When the CIDCW_END Ines~a~ representi~ the end of a CIDCW event is sent by the local modem processor, the carrier-drop-di~col-nect timers (S10 reg~fs) of both local and remote modems are restored to an applopliate value.
With respect to the oper~tion~l sequçnces of FIGS. 3 and 4, the local modem plocessor 126 as well as the remote modem plOCcSSo~ 146 should both include the 15 cl~h~n~ed sorl.. ~uc applir~t~)ne accol~llg to the various embo~h~p ~ iec1osed herein. A
second embo~imPnt is di~closed herein in conne.;~ with FIGS. 5 and 6. This second embodiment equips the local modem processor with çnhan~ed soflwale. The remote modem may, but need not, include such enh~nced software. and it is expected that the remote modem would generally include convention~l software. In this lll&m~el, enhqn~,ed 20 modems may adv~n~eou~ly exploit the techniques di~closPd herein when engag~Pd in c~ c~l;olle with con~lel-lional modems.
FIG. S sets forth an operational sequence to be pe.rolll,ed by the local modem accol~ g to an embodimpnt ~ieclosed herein, and FIG. 6 sets forth an o~.~ional ~1~,en~e to be.performed by a remote modem in l~,~ponse to the operational s~uence of 2s FIG. 5. In this eY~mple, the local modem is e~ ;ppcd with the en~nGed SorL-. al~, of FIG.
5, but the remote modem, equip~ed with con~nl;nn~l s~)rl .~c, responds to the local modem of P~G. S by pe~ rn....;,-g the opel~tions of PIG. 6.
RP-f~Prn~ now to FIG. 5, the program co.h~Pnwc at block 501. The ca~rier~rop timer (S10 ) register is m~nll~lly set in the local modem to an appl~,pl~t~, and/or desired 30 value (block 503). A modem-to-modem co~ un;c~tionc link is established between the 17 - 21726Sl local modem 124 and the remote modem 144 (block 50S). The first t~Plephnn;c device 100 detects an alerting signal sequence (block 507) indicative of the receipt of a third-party incoming ~lephonP call. At block 509, a test is performed to asceltaill ~.hell-~ or not the alerting signal sequence received at block 507 is the first alerting signal sequenr,e l~ce;ved over the past n seconds, wherein n is greater than or equal to ap~ro~i,l,ately 10 seconds.
The ~fflrrn~tive branch from block 509 leads to block 511 where the first modem does not send an ACK signal to the SPCS. The SPCS restores the signal path to the remote modem after time-out (block 513), and modem-to-modem cQrnmuni~?tion~
tom~tic~lly resume without retrain (block 515). Program control then loops back to 0 block 505.
The n egalive branch from block 515 leads to block 517 where the first ~l~phnnicdevice 100 responds to the alerting signal sequence by sen~ing an ACK signal to the SPCS. The first telephonic device 100 then lece;ves FSK data from the SPCS that inrl~ldes caller ir~entifi~-atir)n (CID) information pel~inillg to the identity of the calling party. The local modem processor 126 downloads the CID information to the user erf~^e 128 and the user interface prompts the user with this CID inf~rrn~tion At block 523, the user of first telephonic device 100 must decide whether or not to accept the in~oming third party call. The user is aided in this task by the CID inform~tion displayed on user interface 128. User interface 128 instructs the user to enter the appr~pliate input if it is desired to accept the third party call, and/or instructs the user to enter the applupliate input if it is not desired to accept this call. If the user wishes to accept the call, program control advances to block 525 where the first telephQni~ device 100 flashes the switch hook, h~lu.;~g the central ~wi~hillg office 108 to couple tip/ring line 106 to the third-party inco,ning call. The user co~ n~ni~tes with the thW party (block 527), and, at block 529, the thW party call is t~rmin~ted At block 531, the central s~. it~l,ing offioe 108 dicconnecls the third tip/ring line 116 from the first tip/ring line 106.
However, if first telephonic device 100 is equipped with the appr~p~iate software, it is not nece~ for the central ~wilcl~ing ûffice108 to drop the third-party co~neel;on The neg~ive branch from block 523 leads to block 533 where the local modem sends a retrain signal to the remûte mûdem. The local and remote modems then ~ ` 18 2172651 .
commPn~e retrain procedures, and the program loops back to block 505. The opergtinnsl ence of FIG. S differs from that of FIG. 3 in several lcspec~c~ For e~h~ le, instead of e rre;lively disabling the carrier-drop-~;scol-nr,~l timer (S10 register) during the o~.ul~;nce of a CIDCW call waiting event, the method of FIG. 5 pprm~mpntly presets the S10 l~g~t~,.
S to an applopliate value, i.e., 3 SeCQr'dS, SO that the local modem will remain in an off-hook state during communications block-outs caused by call waiting events. Note that this S10 l~,giS~l setting of 3 secon~s will provide l~connhle modem perform~nr,e in the event of an actual ca rier loss not caused by a call waiting event. When a call waiting event does occur, the local modem simply ignores the CIDCW alerting signal ~uencP~ without 10 ~ n~ g an ACK signal to the central s..ilcl..i~g of fice 108. In some system applir~tions~
the oper~tion~l sequence of FIG. 5 is n~ fiPd such that the user of first ~Plephnnic device is imme~i~tely pr~l-lpled upon receipt of a first alerting signal sequence without being provided with CID information.
After the first alerting signal s~ll~Pnce is received at the local modem, modem-to-15 modem comm~mic~tiot ~ resumes shortly after the SPCS restores the comm~)ni~tion~path. RetMininE procedures are not necp~ss~l y to restore modem-to-modem commllnir,~ti~n~ Ten seconds after receipt of the first alerting signal sequence, the second alerting signal se~uence is sent out by the SPCS. At this time, the local modem responds with an ACK signal indicative of the det~P-cP()t- of the second alerting. Then, the SPCS
20 I~;,pGnds to the ACK signal by ~n(linE out FSK data includinE caller iderltific~tion (CID) inform~tion The CII:) informatiorl iS displayed on user interf~ce 128, which may include a COI~ut~ screen that notifies the user as to the e~ nce and identity of a new inco...i.~E
caU from a third party. Based upon the CID inform~tion p~n~cd on the user i~ f~
the user may justify the impo~ Ue of the cali, and decide ~,. heth~r or not to answer the 25 third, party call.
If the user chooses not to answer the caU, then modem-to-modem col...~ .icationsare reestablished after a full retrain procedure. Due to the fact that the CID inform~tion usually conlh;~-c the third party caller's telephone number, the user is provided with the oppo~ y to return the third party call at a later time, while modem co...~ ic~t;~-ns are 30 rninim~lly disrupted.

217-~b~ l ~l~a~s ` 19 If the user elects to answer the third party call, the first tpl~phonic device 100 flashes the switch hook, instructing the central switching office to conne~l the third-party incû~ p call to the first tip/ring line 106. The user then pick up the t ~U ~;')1- telephonp set 105 and cû..~ -ications with the third party now commPnce M~ /hile, after expiration of a period of time equal to the value pro~.n~.. ed into its SlO l~g~t~r, the remote modem simply fliC~nn~iL~; from the second tip/ring line 1 12.
FIG. 6 sets forth an operational se-~uence to be pc,Çol,ned by a remote modem in~pOI~ to the operation~l se.luence of FIG. 5. The program commenres at block 601.
At block 603, the carrier-drop timer (SlO register) in remote modem 144 is set to an 10 appnopliate or desired value. A stable modem-to-modem communic~tionc link is established belween local modem 124 and remote modem 144 (block 605). Upon the oc~iu l~nce of a CIDCW call waiting event at local modem 124, communi~ation~ to and from remote modem 144 are blocked by SPCS 110 (block 607). At block 609, a test is performed to ascel~il~ whether or not the block-out of block 607 is the first block-out 5 that has been applied to the remote modem during the previous n seconds, wherein n is greater than or equal to approximately 10 seconds. The affirmative branch from block 609 leads to block 621, and the negative branch from block 609 leads to block 611.
At block 621, the SPCS 110 restores the modem-to-modem comml)nicationc link shor~y, i.e., in m secon~s, where m is less than app~ tely 1.2 seconds. The modem-20 to-modem co~ hlion~ link ~utom3t~ ly l~.ulles without retrain (block 623), and the program loops back to block 605.
At block 613, which is executed as the negative branch Ieading from block 611, atest is pe,rollned to ascertain whether or not the carrier-drop timer (S10 register) has timed out. If so, the remote modem ~isco~npct~ from the second tip/ring line 112 (block 2s 615). If not, the program performs a test to asce.~in whether or not the remote modem ~,ce;~es a retrain signal (block 617). If not, the program loops back to bloc~ 613. If so, the program ad~ances to block 619, where the remote modem starts a retrain procedure.
The program then loops back to block 605.
Various ~ch~ ues have been described in conjunction with ~IGS. 3-6 that enable 30 CIDCW suks~rihers to receive CID inform~tion while engaged in modem-to-modem `` 2172651 communic~tions. These procedures process modem-to-modem cQm..~)ni~ ~tions ~.t~,l"ptions caused by CIDCW call-waiting events, such that modem opPr~tion~
gr~c~funy conl;nue Pu~ ant to a first embodimpnt~ which .c~ s the use of enhanced modem sorlw~e at both the local as well as the remote m~em full interope~bility is 5 p~ ,;ded between both modems and the CIDCW service. The modem user can switch back to modem operation without re-dialing after al~. e.~g an ;~co~ third-party caLL
A second embodiment is useful in conj~ ;on with remote modem.~ that are only ~uipped with eYisting, non-enh~nced sorl~ e. This embodiment l~uu~s the use of el~ n~Rd software only at the local modem. However, the modem-to-modem 10 co~ nl~nic~ti~n~ link belween local and remote modems is not l~co-~ble once the local modem user ar~e.~ the third-party call. This embodiment is adv~nta&P~ollc in that cv~tomP,~ may prefer not to hold the remote modem, thereby avoiding on-line service charges that may be based upon the length of time that these services are ~ce-~dAlthough the local modem user is provided with CID information that may be helpful in 15 deciding whether or not to accept an in-~oming call from a third party, the deci~ion as to whether or not to accept a third party in- oming call may also be based upon the relative inte,...lplablility of the modem appli~ ;on the user is ~;u~ ly engaged in. If the loss of a modem c~ -P~,!;on will not impose any undue incon~enience in a given ,in,~t;ol~ the user may simply answer the third party call.

Claims

1. A method of providing interoperability between a first modem and a caller identity delivery on call waiting (CIDCW) service that operates when a communications link is established between the first modem and a remote modem, the CIDCW service, upon receiving an incoming call from a third party and directed to the first modem, sending the first modem a first alerting signal sequence including a first portion indicative of the existence of an incoming telephone call from the third party;
and, if the first modem responds to the first portion with an acknowledgment signal, the first alerting signal sequence further including a second portion specifying the identity of the third party caller;
the CIDCW service sending the first modem a second alerting signal sequence including a first portion indicative of the existence of the incoming telephone call from the third party;
and, if the first modem responds to the first portion of the second alerting signal sequence with an acknowledgment signal, the second alerting signal sequence further including a second portion specifying the identity of the third party caller;
THE METHOD CHARACTERIZED BY THE FOLLOWING STEPS:
(a) the first modem, upon receipt of the first portion of the first alerting signal sequence, not sending an acknowledgment signal to the CIDCW service; and (b) the first modem, upon receipt of the first portion of the second alerting signal sequence, sending an acknowledgment signal to the CIDCW service.

2. A method of providing interoperability between a first modem and a caller identify delivery on call waiting (CIDCW) service that operates when a communications link is established between the first modem and a remote modem, the remote modemhaving a carrier drop register for storing a value indicative of the time duration for which the remote modem will hold a communications link in the absence of receiving a modem carrier over the communications link;
the CIDCW service, upon receiving an incoming call from a third party and directed to the first modem, sending the first modem a first alerting signal sequence including a first portion indicative of the existence of an incoming telephone call from the third party;
and, if the first modem responds to the first portion with an acknowledgment signal, the first alerting signal sequence further including a second portion specifying the identity of the third party caller;
the CIDCW service sending the first modem a second alerting signal sequence including a first portion indicative of the existence of the incoming telephone call from the third party;
and, if the first modem responds to the first portion of the second alerting signal sequence with an acknowledgment signal, the second alerting signal sequence further including a second portion specifying the identity of the third party caller;
THE METHOD CHARACTERIZED BY THE FOLLOWING STEPS:
(a) the first modem receiving the first portion of the first alerting signal sequence;
and (b) the first modem sending a message to the remote modem instructing the remotemodem to set the carrier drop register to a time duration at least as long as the duration of the first and second portions of the second alerting signal sequence.

3. The method of claim 2 further including the step of:
(c) the remote modem, upon receiving the message from the first modem in step (b), sending the first modem a confirmation signal, the remote modem setting its carrier.
drop register to the time duration specified by the message received from the first modem.

4. A method of providing interoperability between a first modem and a caller identity delivery on call waiting (CIDCW) service that operates when a communications link is established between the first modem and a remote modem, the remote modemhaving a carrier drop register for storing a value indicative of the time duration for which the remote modem will hold a communications link in the absence of receiving a modem carrier over the communications link;
the CIDCW service, upon receiving an incoming call from a third party and directed to the first modem, sending the first modem a first alerting signal sequence including a first portion indicative of the existence of an incoming telephone call from the third party;
and, if the first modem responds to the first portion with an acknowledgment signal, the first alerting signal sequence further including a second portion specifying the identy of the third party caller;
the CIDCW service sending the first modem a second alerting signal sequence including a first portion indicative of the existence of the incoming telephone call from the third party;
and, if the first modem responds to the first portion of the second alerting signal sequence with an acknowledgment signal, the second alerting signal sequence further including a second portion specifying the identity of the third party caller, THE METHOD CHARACTERIZED BY THE FOLLOWING STEPS:
(a) the first modem, upon receipt of the first portion of the first alerting signal sequence, not sending an acknowledgment signal to the CIDCW service;
(b) the first modem, upon receipt of the first portion of the second alerting signal sequence, sending an acknowledgment signal to the CIDCW service; and (c) the first modem sending a message to the remote modem instructing the remotemodem to set the carrier drop register to a time duration at least as long as the duration of the first and second portions of the second alerting signal sequence.

5. The method of claim 1 wherein the first portion of the first alerting signal sequence and the first portion of the second alerting signal sequence each include an audible subscriber alerting (SAS) signal, and a customer premises equipment alerting (CAS) signal.

6. The method of claim 3 wherein the first portion of the first alerting signal sequence and the first portion of the second alerting signal sequence each include an audible subscriber alerting (SAS) signal, and a customer premises equipment alerting (CAS) signal.

7. The method of claim 1 wherein the second portion of the second alerting signal sequence includes FSK data specifying the identity of the third party caller.

8. The method of claim 3 wherein the second portion of the second alerting signal sequence includes FSK data specifying the identity of the third party caller.

9. Apparatus for providing interoperability between a first modem and a caller identity delivery on call waiting (CIDCW) service that operates when a communications link is established between the first modem and a remote modem, the CIDCW service, upon receiving an incoming call from a third party and directed to the first modem, sending the first modem a first alerting signal sequence including a first portion indicative of the existence of an incoming telephone call from the third party;
and, if the first modem responds to the first portion with an acknowledgment signal, the first alerting signal sequence further including a second portion specifying the identity of the third party caller;
the CIDCW service sending the first modem a second alerting signal sequence including a first portion indicative of the existence of the incoming telephone call from the third party;
and, if the first modem responds to the first portion of the second alerting signal sequence with an acknowledgment signal, the second alerting signal sequence further including a second portion specifying the identity of the third party caller;
THE APPARATUS CHARACTERIZED BY THE FIRST MODEM
INCLUDING:
(a) a modem signal transmitter; and (b) a modem signal receiver coupled to the modem signal transmitter;
wherein, in response to the modem signal receiver receiving the first portion of the first alerting signal sequence, the modem signal transmitter not sending an acknowledgment signal to the CIDCW service; and wherein, in response to the modem signal receiver receiving the first portion of the second alerting signal sequence, the modem signal transmitter sending an acknowledgment signal to the CIDCW service.

10. Apparatus for providing interoperability between a first modem and a caller identity delivery on call waiting (CIDCW) service that operates when a communications link is established between the first modem and a remote modem, the remote modem having a carrier drop register for storing a value indicative of the time duration for which the remote modem will hold a communications link in the absence of receiving a modem carrier over the communications link;
the CIDCW service, upon receiving an incoming call from a third party and directed to the first modem, sending the first modem a first alerting signal sequence including a first portion indicative of the existence of an incoming telephone call from the third party;
and, if the first modem responds to the first portion with an acknowledgment signal, the first alerting signal sequence further including a second portion specifying the identity of the third party caller;
the CIDCW service sending the first modem a second alerting signal sequence including a first portion indicative of the existence of the incoming telephone call from the third party;
and, if the first modem responds to the first portion of the second alerting signal sequence with an acknowledgment signal, the second alerting signal sequence further including a second portion specifying the identity of the third party caller;
THE APPARATUS CHARACTERIZED BY THE FIRST MODEM
INCLUDING:
(a) a modem signal transmitter, and (b) a modem signal receiver coupled to the modem signal transmitter;
wherein, in response to the modem signal receiver receiving the first portion of the first alerting signal sequence, the modem signal transmitter sending a message to the remote modem instructing the remote modem to set the carrier drop register to a time duration at least as long as the duration of the first and second portions of the second alerting signal sequence.

11. The apparatus of claim 10 wherein the modem signal receiver includes means for receiving a confirmation signal from the remote modem subsequent to the remote modem receiving the message from the modem signal transmitter.

12. Apparatus for providing interoperability between a first modem and a caller identity deliver on call waiting (CIDCW) service that operates when a communications link is established between the first modem and a remote modem, the remote modemhaving a carrier drop register for storing a value indicative of the time duration for which the remote modem will hold a communications link in the absence of receiving a modem carrier over the communications link;
the CIDCW service, upon receiving an incoming call from a third party and directed to the first modem, sending the first modem a first alerting signal sequence including a first portion indicative of the existence of an incoming telephone call from the third party;
and, if the first modem responds to the first portion with an acknowledgment signal, the first alerting signal sequence further including a second portion specifying the identity of the third party caller;
the CIDCW service sending the first modem a second alerting signal sequence including a first portion indicative of the existence of the incoming telephone call from the third party;
and, if the first modem responds to the first portion of the second alerting signal sequence with an acknowledgment signal, the second alerting signal sequence further including a second portion specifying the identity of the third party caller;
THE APPARATUS CHARACTERIZED BY THE FIRST MODEM
INCLUDING:
(a) a modem signal transmitter, and (b) a modem signal receiver coupled to the modem signal transmitter;
wherein, in response to the modem signal receiver receiving the first portion of the first alerting signal sequence, the modem signal transmitter not sending an acknowledgment signal to the CIDCW service, wherein, in response to the modem signal receiver receiving the first portion of the second alerting signal sequence, the modem signal transmitter sending an acknowledgment signal to the CIDCW service, wherein, in response to the modem signal receiver receiving the first portion of the first alerting signal sequence, the modem signal transmitter sending a message to the remote modem instructing the remote modem to set the carrier drop register to a time duration at least as long as the duration of the first and second portions of the second alerting signal sequence.