Robo Call Regulations Are blocking Answering Service Call Transfers

Answering services (and Infotel Systems) both have a common threat to their operations. The ability to transfer a caller to a destination and show the original callers Caller ID.

In this article, we use this example call flow. Patient 555-1111 calls medical office clinic 666-2222 that forwards to answering service 777-3333. The  answering service then forward the patient  to Dr. cell phone 888-4444.

The Caller ID of the patient may cause the call to fail at the arrow points  as listed in red.  Patient 1 —> Clinic 2 –> transfer 1 –->Answering Service 3 — transfer 2 –> Dr. Cell Phone 4.  The reason is government Robo Call regulations due for completion in June of 2021. It’s called Stir/Shaken.

How does STIR/SHAKEN (Call Authentication) break the above call flow?

We want Calling Party Number (CPN) 555-1111 to becomes the Caller ID (CID) that the doctor sees on their cell phone.  Yet, the Stir/Shaken call filters breaks this during transfer 1 and 2 as sending the CPN of 555-1111 that you don’t own is considered Caller ID spoofing.

The carrier involved along transfer 1 or 2 will flag the call as suspicious and not mark the call with a grade of A. The specific Stir/Shaken rules are

  • Full Attestation (A) – You are sending a CPN that is a DID on the SIP trunk. Your carrier say’s I know you and I know that number. I will route your call with a grade of A.
  • Partial Attestation (B) – You send a CPN that is NOT a DID on the SIP trunk. Your carrier say’s I know you but I don’t know that number. I will route your call with a grade of B.
  • Gateway Attestation (C) – International calls. The true source of most spam.  This is a C grade. The answering service is not going to generate this type of call. But, we receive these calls and this is what started the issue.

Carriers are currently taking an all or nothing approach. They attest at a level of A or C, not the B.

Trouble Shooting (draft)

You can prove Stir/Shaken by forwarding calls with a non native CPN to T-mobile cell phones.  T-mobile will accept the call but send the caller straight to voice mail.

For technical people, we understand that SIP code 608 may be returned as an error code to your VoIP system and this code may become the Industry standard error for C level attestation calls.

Solution To This Issue

  1. In the example for the 2nd transfer, one would stop sending the patients Caller ID of 555-1111 to the doctor. You would need to send the account number 777-3333 to the doctor cell phone 888-4444. But, this is likely not desired.
  2.  We are working on that. It involves originating A or B level calls via a certification between your answering service switch and your carrier. We are working on this.