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STIR/SHAKEN methodology with Flowroute

For inbound calls to customers, our current plan is to provide both of the following STIR/SHAKEN-based insights:
  1. TN validation info via the ‘verstat’ tel URI, a parameter in either the P-Asserted Identity (PAI) header field or the FROM header field. This parameter will contain one of the following 3 values denoting the result of a TN validation check:
    1. TN-Validation-Passed
    2. TN-Validation-Failed
    3. No-TN-Validation
  2. If we get a "TN-Validation-Passed” result in the verstat, we will prepend “[V]” to the CNAM, right-truncating CNAM if the addition of “[V]” causes the 15-character limit to be exceeded.
    1. For calls that have the above-mentioned verstat result, we’re also putting logic in place that will overwrite any CNAM content that originating networks or customer’s PBX would supply, so that the pre-pended [V] doesn’t inadvertently communicate invalid/nefarious CNAM content.
    2. Finally if the CNAM content from our content-provider is either blank or the response is NULL, the CNAM will simply be “[V]”
    3. All other calls will be have normal CNAM treatment.
A couple of additional comments regarding inbound calls:
  1. We do not plan to block inbound traffic based on a STIR/SHAKEN verification result at this time
  2. The spirit of offering both (1) and (2) together is to allow customers who can handle/parse SIP headers to apply their own treatment, if they so choose, while also providing for others who cannot; the CNAM-based approach solves for a large variety of end-customer-device restrictions without the need for service providers to individually do so.
For outbound calls from customers, generally speaking,
  1. Calls from TNs that a customer purchased from Flowroute, and are associated with that specific customer’s Flowroute account, should get attestation A.
  2. Calls from TNs other than those that a customer purchased from Flowroute, should get attestation B
  3. Calls from a customer whose Flowroute account is in ‘Pending’ status will get attestation C
  4. Calls from invalid TNs (invalid per North American Numbering Plan) or with caller ID “Anonymous” will get attestation C
  5. We will pass-through, unaltered, any attestation we receive on calls arriving at Flowroute.
As is the case with inbound calls, we do not plan to block calls based on a particular attestation level at this time.
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