Specifications

MBG Engineering Guidelines, Release 8.0

5 SIP Trunking

5.1 Overview

A “SIP trunk” in the context of MBG is simply a pair of endpoints, defined by their IP addresses and signaling

ports. One of the endpoints is usually your ICP (MCD (3300 ICP) or 5000 CP), and the other is your SIP

provider’s firewall or SBC.

A trunk can have any number of “channels,” each of which corresponds to an active media stream. A channel

license is required for each active channel, so you will need enough channel licenses to cover the maximum

number of active calls. As an analogy, an ISDN PRI link contains 23 B channels for audio and one D channel for

signaling, and can carry a maximum of 23 simultaneous calls. This would be equivalent to a SIP trunk with 23

channel licenses.

Note: On the MCD (3300 ICP), the MBG is configured as an outbound proxy in the Network Element form.

Warning: In the 5.X releases, the SIP trunk connector listened on UDP port 5064 by default. As of MBG

6.0 the SIP connector can handle device endpoints and sip trunks, so UDP port 5060 is used for both

devices and SIP trunks. The Legacy Connector can no longer be re enabled as of MBG 8.0. If UDP port

5064 is in use then you will need to contact your SIP Trunk provider to have their equipment changed to

use MBG's UDP port 5060 before upgrading MBG to 8.0.

Warning: A SIP server requires functional DNS even if all devices are configured to use IP addresses

instead of FQDNs. MBG is no exception. Failure to provide MBG with a working DNS resolver or

preventing MBG from reaching the Internet DNS root servers can cause delays or failures in call setup.

5.2 Bandwidth Requirements

Please see the section Sizing Your Installation on page 40.

5.3 Resilient Trunk Configuration

This section describes a sample resilient SIP trunk configuration using two ICPs and two MBGs.

First, configure resiliency between the ICPs.

On ICP “A”:

• Create a Network Element Assignment for MBG “A” (as type Outbound Proxy) and another for the SIP

provider’s SBC (as type Other). Create a SIP Peer Profile for the SBC using MBG “A” as the Outbound

Proxy.

• Add a Network Element Assignment for MBG “B” (as type Outbound Proxy) and create another SIP Peer

Profile for the SBC using MBG “B” as the Outbound Proxy.

• Program a Route List in ARS with SIP peer “A” and SIP peer “B”. Then program ARS Digits Dialed such

that outgoing calls use the new route list.

Repeat the above configuration on ICP “B”, except reverse the order of trunks in the route list so that “B” comes

before “A”.