Date Added: Aug 2011
As traditional TDM PBXs have progressively been replaced with IP-PBXs and unified communications systems, vendors have been called upon to integrate these systems with the North American E9-1-1 emergency call system. Among other characteristics, E9-1-1 requires automatic location identification of the caller who dialed 911. With a traditional PBX, the physical location of each TDM desk phone was associated with its PBX port at the time of installation. Assuming that association was unchanged, the mapping of a phone number to a location was static and easily documented. IP PBXs use IP desk phones that can be connected to any Ethernet port.