According to the present invention, a voice storage device includes a port control unit for monitoring a service state of a port of a PBX extension circuit, and a private branch exchange is configured to transmit, upon receipt of an incoming call, an incoming signal including caller information and the...http://www.google.es/patents/US6870908?utm_source=gb-gplus-sharePatente US6870908 - Voice storage device and incoming call answering system
Voice storage device and incoming call answering system
