Send originating extension number in p-asserted ID for stir/shaken

[lcking919]

Is it possible to send the originating caller ID as the extension number in the p-asserted ID field over a SIP trunk? This would be needed in order to properly sign a call for stir/shaken. We have tons of users using the same caller ID and need to send the actual extension of the caller who originated the call.

 

[YiannisH_3CX]

You want the extension number (e.g. 100) or the outbound caller ID of the extension? As far as I know if your caller ID is legit and belongs to your trunk even if PBX users are using it it's not an issue for your provider to sign calls.
Or are you talking about forwarded calls that send the originating caller ID and you also want your called ID included in the Invite?

 

[lcking919]

We are wanting to specify the user which made the call in the P-Asserted ID via the user's extension number, yes. Is there any way to accomplish this?

 

[YiannisH_3CX]

Normally 3CX does not send extension numbers through trunks for security reasons. You can do it by setting the extension number as the extensions outbound caller ID and manipulate the trunks outbound parameters accordingly but you will need to set it up so that other headers do not also send the outbound caller ID.
This will not work if you have a caller ID set in your outbound rules and might break some call scenarios.

Which provider are you using that requires this? As far as I know STIR/SHAKEN does not require this to sign calls. Also will the provider be stripping the extension number from the Invite?

 

[leejor]

Most providers require that a valid, PSTN caller, ID be sent on outgoing calls, not a 3 or 4 digit extension number. Won't the DID number, as datafilled in the outbound caller ID, for each each extension, work?