Case Study:  Wabash Communications Implements STIR/SHAKEN on hybrid SIP/TDM Network 

Summary

  • Wabash Communications is a regional telecommunications service provider based in Illinois
  • They wanted to implement STIR/SHAKEN help eliminate robocalls and improve subscriber answer rates
  • However, with a mix of SIP and TDM trunking, standard STIR/SHAKEN would be incompatible
  • Wabash implemented Out-of-Band STIR/SHAKEN by pairing TelcoBridges ProSBC and TransNexus ClearIP
  • According to Dave Frigen, Chief Operating Officer at Wabash Communications “The ProSBC/ClearIP solution has run flawlessly…not a single failure since day 1”

“Our participation in the STI-GA board has been to address issues that impact the many NTCA member operators with TDM equipment or interconnects”
– Dave Frigen, Chief Operating Officer at Wabash Communications.

Background

Founded in 1952, Wabash Communications Coop provides telephone, broadband and television services to subscribers in South Central Illinois.  Other services include home & business security, mobile device repair, and VoIP services.  Locally owned by its 3,500 members, Wabash has approximately 13,000 subscribers, and 110 employees.

As an early participant in ATIS standard development, Wabash has been representing rural telephone operator members of the NTCA, holding a seat on the STI Governance Authority board, guiding many of the STIR/SHAKEN decisions.

“Our participation in the STI-GA board has been to address issues that impact the many NTCA member operators with TDM equipment or interconnects” said Dave Frigen, Chief Operating Officer at Wabash Communications.

“We wanted to deliver a highly reliable STIR/SHAKEN solution for our subscribers, without significant expense”

Challenges

Like virtually all voice telephony consumers, Wabash subscribers have been suffering from illegal robocalls, a source of much annoyance and a conduit for fraud.   As a result, consumers are less likely to answer calls from phone numbers they do not recognize.  Commercial subscribers that have legitimate business with their customers are suffering from significantly lower call answer rates.  Whether it’s a prescription refill, doctor’s appointment reminders, school closings, or reverse 911 calls, there are legitimate cases where businesses, schools, and government agencies need to urgently communicate with subscribers.  Improving subscriber trust in the public phone network is a major goal of the STIR/SHAKEN framework, a requirement of the TRACED Act signed into law in 2019.

“We wanted to deliver a highly reliable STIR/SHAKEN solution for our subscribers, without significant expense”

To implement STIR/SHAKEN at Wabash Communications, there were a number of technical and business challenges:

  • The SIP-based Ribbon C15 softswitch at the core of the Wabash network did not support STIR/SHAKEN. To add the feature would require an expensive upgrade.
  • The interconnect trunks that pass traffic to other operators are SS7 based and are not compatible with the original SIP-based STIR/SHAKEN framework.
  • Parts of the Wabash network infrastructure are not yet fully depreciated. Replacing this equipment would result in a significant write-down expense.

“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.”

Based on his participation in the ATIS STI-GA board discussions, Dave Frigen knew an effort was underway to standardize Out-of-Band STIR/SHAKEN, an innovative way to implement STIR/SHAKEN for hybrid SIP/TDM and pure TDM operators that would be compatible with the challenge at Wabash, integrated into his existing Ribbon C15 softswitch.

“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.”

Solution

To implement Out-of-Band STIR/SHAKEN, Dave and his team at Wabash Communications augmented his existing Ribbon C15 softswitch with TelcoBridges’ ProSBC and TransNexus ClearIP as show below:

In this configuration, additional SIP trunks were configured on the C15, providing interfaces to TelcoBridges’ ProSBC and the TransNexus ClearIP service, facilitating both STIR/SHAKEN Authentication and Verification services.

The Ribbon C15 call routing rules were modified to direct both inbound and outbound call traffic to ProSBC via the appropriate SIP trunk, passing SIP signaling information during the call setup process.   ProSBC then forwards the call details to ClearIP SIP messages for authentication or verification.

Depending on whether the call is inbound or outbound, the handling by ClearIP varies:

  • In the case of outbound traffic, the ClearIP authentication service uses Wabash configured attestation rules to create an identity token, posting the token on the terminating service provider’s Call Placement Service (CPS).
  • For inbound traffic, the ClearIP verification service retrieves the identity token, checking for validity, and if the call passes verification, adds a “[V]” to the CNAM field, alerting the called party of the validation status. The call information, including the CNAM information, is passed to the C15, completing the call to the called subscriber.

This architecture put ProSBC in the Wabash private VMware cloud and uses ClearIP as a cloud service, providing not only security and reliability to the solution, but scalability as well.  With this architecture, should a failure occur in either ProSBC or ClearIP, the impact would result in a loss of the STIR/SHAKEN features, but not otherwise disrupt call handling for Wabash and their subscribers.   This architecture also alleviated reliability concerns for Dave and his team.

“The ProSBC/ClearIP solution has run flawlessly…not a single failure since day 1”

Results

With the completion of the implementation, Wabash Communications subscribers now have the benefit of seeing caller-ID with a “[V]” in the caller name display, confirming that the caller ID has been verified and is not spoofed.   With the increasing number of other operators now supporting STIR/SHAKEN, verification will become more common and increase subscriber confidence.

By digitally signing the outbound calls, Wabash strides forward toward progress in FCC mandates while improving call answer rates.

After nearly 12 months of continuous operations, Dave Frigen reported that the solution has performed without failure.

“The ProSBC/ClearIP solution has run flawlessly…not a single failure since day 1”

Benefits of the solution:

  • No upgrades were required to the Ribbon C15 softswitch, saving tens of thousands of dollars.
  • Quick to implement with little or no subscriber disruption.
  • All outbound calls now have a published attestation posted to the terminating service provider CPS.
  • Subscribers now benefit from “[V]” display for verified calls from outside the service area, reducing the risk of answering fraudulent calls.
  • Wabash now has the option for robocall prevention on inbound calls, provided by ClearIP.
  • A cost-effective, scalable, subscription-based business model that fits Wabash Communications needs.
  • Proven high reliability.

Recognition as being one of the first hybrid SIP/TDM networks to implement STIR/SHAKEN.

Learn More:

To learn more about the elements and components outlined in this case study, visit:

Wabash Communications at: https://wabash.net
TelcoBridges ProSBC at: https://www.prosbc.com
TransNexus ClearIP at: https://www.transnexus.com

  • Case study PDF

    On the way soon… be sure to check back