Hi
@kelvin
Let's consider the following example just to make things more clear.
Assume that you have this main trunk number: 123456789100
And you have extension 101,102,103,...,199
If i got it right, you want every extension to have its own DID? For example:
Extension 101 >> DID 123456789101
Extension 102 >> DID 123456789102
...
Extension 199 >> DID 123456789199
Now let's take extension 101. When dialing out you want it to send 123456789101 as the caller ID?
And what about when someone calls back to 123456789101? Do you want to route the call to extension 101?
This assumes that you own these DIDs because even if for some reason the provider allows you to send out the specific caller IDs, what would happen when they are called back. They need to route back to your trunk.
Assuming that you own all these DIDs, you need to clarify with the provider as to what SIP field they require this info to be sent when calling out.
Then you change the Outbound Caller ID in your Extensions Settings to reflect the DID of each one and in the Outbound Parameters of your SIP Trunk's Settings you need to set the SIP field that your provider told you as "
OutboundCallerid Outbound caller id taken from Extension settings in management console"
Now for incoming calls, you will need to add all these DIDs in your SIP Trunk's Settings >> DIDs Tab and then add an inbound rule for each DID to route to the required extension.