Session Initiation Protocol trunking

Last Updated : Mar 31, 2019 |

IP Office uses Session Initiation Protocol (SIP) trunks to allow users to take advantage of telephony services offered by internet service providers (ISPs). In many cases, telephony services offer substantial savings in comparison to traditional exchange lines. To help enable the SIP Service Provider, Avaya offers a SIP Compliance Testing Program (GSSCP) that will validate the operation of IP Office with the ISPs SIP trunk offering. For more information about Avaya's SIP Compliance Testing Program (GSSCP), see https://www.devconnectprogram.com/site/global/compliance_testing/overview/index.gsp.

IP Office 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 require provisioning of voice compression channels through the installation of VCM modules within the control unit. A license for the maximum required number of simultaneous SIP calls is also needed. Up to 128 simultaneous calls are supported.

IP Office also supports the T38 protocol which allows Fax over IP.

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

Figure : 1. Service provider with Avaya Session Border Controller (recommended)
Figure : 2. Direct connection from the second Ethernet port to the internet through a DMZ port on the router.

To make this configuration secure, the IP Office firewall is set to drop all packets except SIP.
Figure : 3. Connection to ITSP over NAT using third-party STUN servers
Figure : 4. Connection to ITSP through router with ALG to resolves NAT issues
Related information
Internet protocol telephony
SIP servers
SIP endpoint user agents