STIR/SHAKEN for TDM Networks – A New Case Study

By Alan Percy, CMO @TelcoBridges

Wabash Communications Coop in southern Illinois is an example of how STIR/SHAKEN authentication and verification can be accomplished by rural telecommunications service providers with TDM interconnects.

One of the challenges facing smaller and rural service providers is protecting their subscribers from the flood of scammers and illegal robocallers.   Many of these smaller or rural operators have some or all TDM infrastructure in their networks.  The STIR/SHAKEN framework was originally designed for 100% SIP networks, essentially passing over operators with partial or fully TDM network infrastructure.

ATIS, the body driving the STIR/SHAKEN framework has been working on an Out-of-Band STIR/SHAKEN recommendation that should address the needs of TDM service providers.  As I explained in my June 5th, 2020 blog, Out-of-Band (OOB) STIR/SHAKEN uses HTTPS over the Internet to deliver an encrypted identity token from the originating service provider’s Authentication Service  to the terminating service provider’s Verification Service, avoiding the many issues with TDM interconnects and intermediate operators. The result is the same as In-band STIR/SHAKEN – valid calls get delivered as “Verified”, helping the recipient decide whether the call is safe to answer (or not).

One of the early advocates for OOB-STIR/SHAKEN is David Frigen, Chief Operating Officer at Wabash Communications and a member of the ATIS STI-GA Board.  At Wabash, their subscribers were suffering like most of America from illegal robocalls and their scams.

“We wanted to deliver a highly reliable STIR/SHAKEN solution for our subscribers, without significant expense” said David Frigen, COO at Wabash Communications.

But Wabash had some challenges:

    1. A Ribbon C15 softswitch that did not support STIR/SHAKEN and would be expensive to upgrade
    2. TDM trunks to their Interconnect carrier(s) that could not support STIR/SHAKEN
    3. The board wanted to avoid write-down expenses for equipment that was not yet depreciated

“Like many of the NTCA members, we have TDM equipment that is not yet depreciated…we have a fiscal responsibility to our subscribers and owners.”

STIR/SHAKEN ArchitectureWorking with the network team at Wabash, TelcoBridges and TransNexus developed a joint solution that facilitated Out-of-Band STIR/SHAKEN for their existing C15 switch, retaining the TDM interconnect trunks and avoiding an expensive upgrade to the C15.

The solution uses TelcoBridges ProSBC to integrate TransNexus ClearIP, together providing OOB-STIR/SHAKEN services to both in-bound and out-bound call traffic.

Learn more from our NEW case study on Wabash Communications