In a facsimile apparatus with an external telephone unit connected thereto or in a telephone terminal apparatus having telephone and facsimile communication functions, when a particular code signal is sent through a telephone line during a telephone communication being effected, a facsimile communication...http://www.google.de/patents/US5481373?utm_source=gb-gplus-sharePatent US5481373 - Facsimile apparatus and telephone terminal apparatus having voice and image communication functions
