ARCHIVED: What is SDSL?

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Symmetric digital subscriber line (SDSL) is a modem technology that allows data to be sent over existing copper telephone lines at higher speeds than traditional 56k dial-up connections. SDSL supports data rates up to 3Mbps, over 50 times faster than 56k.

SDSL is called symmetric because it supports the same data rates for upstream and downstream traffic. This contrasts to asymmetric digital subscriber line (ADSL), which has lower data rates for upstream traffic. ADSL is more popular for residential users, as it allows normal telephone service over the same wire, and is usually less expensive than SDSL.