Manual

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You may also come across certain PBXs that must deliver their extensions in this way. In order for EarShot IFB to
receive these extensions, a SIP trunk must be created instead of a provider account.
SIP Trunks also differ from normal SIP providers in several ways. Rather than having EarShot IFB “pull” the SIP
channel from a provider, a SIP trunking provider will “push” the channel to a specific IP address of the user. This
means in order to support SIP trunking you need a public, static IP address, and no other devices can be utilizing
the SIP ports at that address.
Unlike normal SIP providers, only a single SIP Trunk is supported on each EarShot IFB mainframe.
The option to add a new SIP Trunk is located in Line Configuration-> VoIP providers-> Add Provider -> SIP
Trunk. Once a new Trunk is created, there will be no option to create another.
Although the settings menu for SIP trunking appears the same as for a normal provider, only a few of them are
meaningful. You should put your trunking provider’s name into the “name” field, choose your codec options (see
normal provider settings) and set the correct SIP port value (usually 5060). Username and Password fields can
be ignored.
You’ll also need to populate the Server/Realm field in the Trunk Settings menu. This will be the IP address (e.g.,
74.94.151.151) of the Trunking provider. Unlike with registered providers, this field should not be populated with
a domain name (e.g., myprovider.com) but needs the actual IP address of the provider’s server. This is required
for matching, as explained below.
Finally, a SIP trunk needs to determine which calls are from your provider, in order to process them to the correct
incoming phone line. This is done via a process called “matching”. The simplest form of matching is the default,
where the source address of incoming calls will be matched to the value in the Server/Realm field, and if correct,
the incoming call will be routed to the proper line.
In some circumstances, this setting isn’t correct and needs to be adjusted. You can access the matching settings
by clicking Show Advanced and looking under the Extra Settings section. The two options of interest for trunks
are:
1 Trunk Incoming Match Parameter - Selects which field within the incoming call parameters
(sent at call setup time by the provider) is used for the match. This can be the Network Address
(default) or the Destination Number field.
2 Trunk Incoming Match - This is the field where you enter the text that will be matched by the
system to the incoming call.
If the Network Address option is chosen, It’s OK to leave the Trunk Incoming Match field blank - this is the
default configuration, and the system will use the Server/Realm field entry for the match.
Alternately, you can input a different IP address to be matched, in the case where the source IP of the call is
different than the Server/Realm entry.
Alternately, if the Destination Number selection is chosen, the Trunk Incoming Match field must be populated.
The system will look at the Destination Number field of incoming calls and accept only calls with literal matching
text. This field can also be set as a “regular expression” for a dial plan, which is a more complex topic and can be
handled by Comrex support. As an example, entering the following value in the field:
^(1\d{3}555210\d)$