Specifications

IP Office Product Description

IP Office 4.2

Page 146

Issue 18.b.- (08 July 2008)

Session Initiation Protocol (SIP)

IP Office 4.0+ introduces SIP trunking. SIP trunks allow IP Office users to take advantage of new telephony

services being offered by ‘Internet Telephony Service Providers (ITSPs)’. In many cases, these telephony

services can offer substantial savings in comparison to traditional exchange lines. The IP Office solution allows

all users, regardless of their phone type, to make and receive SIP calls. SIP trunks are handled like any other

line on IP Office, affording all the call routing and toll control needed to manage inbound and outbound calls.

SIP trunks on IP Office require the provisioning of voice compression channels through the installation of VCM

modules within the control unit. RTP Relay is also supported to allow the IP stream through SIP after call

setup. A license for the maximum required number of simultaneous SIP calls is also needed.

There are several possible network topologies for SIP trunk systems, as shown in the following diagrams.

Option 1: Service provider with a Session Border Controller (SBC), which solves NAT traversal issues – this is

the most reliable and preferred method.