An adapter is disclosed which allows attachment of a standard telephone to a computer as a standard peripheral. The adapter converts analog signals of the telephone to digital signals of the computer and vice versa. The adapter can also be a stand-alone device allowing the telephone to be attached to a computer network. The adapter, in this case, contains the computing power to support the necessary data network protocols, and PSTN signalling protocols.In this way voice communication is enabled over a computer network without requiring the computers to be equipped with sound cards.