What is SIP Trunking?

Session Initiation Protocol (SIP) are phone lines much like the old Public Switched Telephone Network (PSTN) or physical Analog copper lines except that they are delivered over IP using the SIP Protocol.

Most Telco’s within Australia are now providing SIP Trunks which can also be called Voice over IP (VoIP), although the 2 terms are different. VoIP uses the SIP Protocol to transmit only voice messages, whereas SIP Trunks can carry all forms of media not just voice calls.

SIP Trunks once ordered simply connect to a PBX much like the old Analog copper services (PSTN and ISDN) but over your Data Network whether it be via a dedicate Voice network or your existing network. Unlike the old PSTN lines where your phone numbers (Direct inward dialling- DID) where assigned to 1 DID per line, with SIP trunks can have a multiple DID blocks, similar to ISDN services.



The introduction of SIP services has allowed for more competition within the Telemarket, the key benefit of this competition is the dramatic drop in cost of Phone Lines and calls. The initial outlay is not as high and there are many other benefits, as seen below.