News / Voice
A 2006 guide outlines a SIP phone system
A 2006 guide for Snom phones sold by ProVu Communications explained SIP as the signaling basis for an IP phone system and contrasted it with a traditional PABX.
Components behind the phones
The guide described a SIP proxy or registrar as a directory for users and registrations, a gateway as the connection to analogue or ISDN telephone lines, and a media server as the source of voicemail, music on hold, conferences and auto-attendant functions. It also noted that a LAN might need more ports or capacity.
ProVu stressed open standards, endpoint intelligence and the ability to use an identifier from different locations. Its examples included home working, multi-site calling and PSTN breakout. Those are design possibilities presented by a reseller, not a guarantee that equipment from different vendors or sites will interoperate without careful routing, network and security work.