In the 3CX, if the sip trunk have many DIDs, the DIDs and extensions can be set as one to one, it means when one extension calls out through the sip trunk, one specific DID will display on the screen of the callee. When anyone dials the DID number from outside, the specific extension will ring too.
In order to realize it, we can refer to the settings below:
The setting for inbound calls:
1.Add all the DIDs in the sip trunk.
2.Add DID Rule, and route the inbound call from the specific DID to the specific extension.
After that, please make sure the DID rule will not conflict with the CID rule, because the inbound call will check the rules from top to down, when the call matches the rule, the call will be processed and will not check the following rules.
The setting for outbound calls:
1.In the setting of extension, add the specific DID to bind the extension.
2.Edit the outbound parameters of sip trunk, and make sure the from:user part will use the outbound caller ID of extension.
From:User Part->”OutboundCallerId” Outbound Caller Id taken from Extension settings In managment console.
3.Create the outbound rule, so that the extension can call out through the sip trunk. Here we can set the prefix, extension and number length and so on.
After that, please make sure the outbound rules will not conflict each other, because the outbound call will check the rule from top to down, and when the rule is matched, the call will be processed and will not check the following rules.
That is all the settings, and we can test the call now.