Architecture for linking multiple internet protocol telephony devices having a common telephone number

An architecture and method for permitting internet telephones assigned to a common telephone number but each having a unique IP address to be used in the manner of telephones and extension telephones in PSTN. A calling agent is provided with the fully defined address of two or more telephony devices. Telephone traffic to or from either of these devices is directed to a call agent, which contacts a gateway, which rings one or both of the telephony devices. This gateway then forms a bridge with a secondary gateway, to which are attached the other telephony devices that are to act as extensions of the first, and combines the audio from both so that they appear to the consumer to act like conventional PSTN extension telephones. This architecture can be used with any Internet Protocol telephony device, including video telephones.