PSTN Trunk DIDs

PSTN Trunk DIDs allow you to assign DID numbers to specific channels of your PSTN interface card(s). 

Unlike SIP or PRI trunks, PSTN trunks do not send a DID number to the PBX. Since the UCX routes all inbound calls based on the DID number, you can map each channel to a pseudo-DID number, then use standard Inbound Routes with the specified DIDs to route your calls. If you do not assign any DID number to your PSTN trunks, then the Catch_Unhandled any DID route will be used to route your call.

E-MetroTel recommends setting the DID field to be the full 10-digit central office phone number that would ring that particular incoming trunk. This allows for easier troubleshooting on issues with incoming calls.  If there is no 10 digit phone number associated with this trunk, for example Nurse Call or Door Phone applications, any number can be assigned that does not interfere with the rest of the UCX dial plan.

You can use the same DID for multiple channels. This would be a common scenario if you have multiple analog lines that are on a hunt group from your provider.

To add a PSTN Trunk DID, perform the following steps:

  1. Open the UCX Web-based Configuration Utility
  2. From the PBX tab, select PBX Configuration
  3. From the left side column, under Inbound Call Control, select PSTN Trunk DIDs
  4. Fill in all the fields and press the Submit Changes button

Field Description
Channel Define the channel number. If you have a 4 port card, the channels would be ports 1-4.
Description Enter a descriptive name
DID Enter the DID number to be assigned to this channel. This is the DID that will be passed to the inbound routes, so make sure what you define here is the same as the DID field in your Inbound Route configuration.


If you are going to route all 4 channels to the same destination, you can set the DID for all 4 channels to the same DID number. This way you only need to create one inbound route.

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