Adding Stir/Shaken attestation using Transnexus ClearIP Service

Preamble

If you have a requirement to add a Stir/Shaken attestation to calls leaving a FreePBX/PBXact system you can do so with a subscription to the ClearIP service provided by Transnexus. There are a few third party services that will assist with generating S/S attestations for SIP calls, ClearIP does this by means of a SIP signaling mechanism that can't easily be consumed directly by FreePBX. It relies on an external SIP proxy to perform the S/S signature.

Prerequisites

• FreePBX/PBXact version 15/16. Not tested with other versions but will likely work with little or no modification

• Account with Transnexus ClearIP serivce

• A host system to install the in-line SIP proxy

• SIP provider that supports outbound calls by IP authentication

Step 1 - Set up and Configure the in-line proxy

Base instructions are here: https://transnexus.com/clearip-inline-proxy/

Configure the in-line proxy to accept inbound SIP INVITEs from the PBX and to forward the invite to your ITSP.

Configure the ITSP to accept the outbound call SIP INVITE from the in-line proxy.

Add the in-line proxy to the ClearIP account as an SBC

Step 2 - Setup new Trunk on the PBX

With the in-line proxy now set up, it needs to be added as a Trunk. Configure a new Chan_PJSIP trunk with details as follows:

Open

Open

Set Authentication and Registration to None and set the General Settings as necessary for normal PBX calling operation.

Step 3 - Config the Outbound Route

With the Trunk setup to the in-line SIP proxy, add the trunk to the Outbound Route Sequence ahead of the conventional SIP Trunks. Do this for any and all Outbound Routes as needed. Outbound calls will now go out using the in-line proxy to get an S/S SIP Identity header. If the in-line proxy doesn't respond, then the call will proceed out the next configured trunks direct to the provider.