3.6 IP Trunks

Trunk is a term used to describe the connection to the Service Provider as opposed to the connection to the User Phone which is called a "Line". There are many kinds of trunks and there are several kinds of IP Trunks, for example: SIP Trunks, IAX Trunks, and H323 Trunks to name a few IP Trunks. A trunk can be one DS0, an OC192, and up! A trunk can also have multiple connections. For example, a single trunk can have 2,3 or more DS0 connections.

The muPBX utilizes two kinds of trunks: SIP Trunks and PSTN Trunks.

SIP Trunks

The SIP phone registers with the muPBX; its the muPBX's client. To the SIP phone, the muPBX connection is the SIP Phone's trunk. The Service Provider looks to the muPBX as their client and therefore requires the muPBX to register with them. (Note - Some Service Providers do not require registration for clients on VLAN IP networks or who uses IPSec but, this is a discussion for later.)

So, we need to setup the muPBX to register with the Service Provider like we setup the SIP Phones to register with the muPBX. Most of this can be setup in the GUI but I found I had to tweak the users.conf file to get it working properly.

# Name of the Service Provider

# FQDN of the Service provider
host = sip.jnctn.net

username = myusername
secret = mypassword
trunkname = junction  ; GUI metadata
context = DID_junction
group = null
hasexten = no
hasiax = no
hassip = yes
registeriax = no

# Register with the Service Provider
registersip = yes

trunkstyle = voip
insecure = port,invite

# Start timers on all calls.  This will tear down calls that miss SIP Bye messages.
session-timers = originate
session-expires = 300
session-minse = 90
session-refresher = uas

disallow = all
allow = ulaw

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