A telephone central office switch (103) provides Centrex features, including intercom dialing, on central-office-to-PBX (133, 134) trunks (123, 124) by using the 4-wire subscriber feature of the Lucent Technologies 5ESS.RTM. switch to administer trunk ports (113-114) that serve the...http://www.google.es/patents/US5825868?utm_source=gb-gplus-sharePatente US5825868 - Arrangement for providing private-network line features on central-office-to-PBX trunks
Arrangement for providing private-network line features on central-office-to ...
