Check the 608 responses for a Call-Info header. If present, it should contain a point of contact for redress. https://www.rfc-editor.org/rfc/rfc8688.html#section-3.1-3 "If there is a Call-Info header field, it MUST have the "purpose" parameter of "jwscard". The value of the Call-Info header field MUST refer to a valid JSON Web Signature (JWS) [RFC7515 <https://www.rfc-editor.org/rfc/rfc8688.html#RFC7515>] encoding of a jCard <https://www.rfc-editor.org/rfc/rfc8688.html#RFC7095> [RFC7095 <https://www.rfc-editor.org/rfc/rfc8688.html#RFC7095>] object. The following section describes the construction of the JWS.? <https://www.rfc-editor.org/rfc/rfc8688.html#section-3.1-3> You can also look into registering your calling numbers at sites like the two below. It may also help to cover the basics like CNAM and a Directory Listing to improve the "legitimacy" of the numbers. https://registeredcaller.com/ https://www.freecallerregistry.com/fcr/ Some analytics will assume the worst until proven otherwise. You could attempt a low volume, low velocity, high ASR test pattern on an affected carrier to ensure your calling numbers have some positive reputation established before any mass calling. On Wed, Jan 11, 2023 at 7:08 AM Dovid Bender via VoiceOps < voiceops at voiceops.org> wrote:
Hi All,
We are a small ITSP and every so often we have issues with calls that go to T-Mobile. We sign all our calls with our cert. Lately we have been getting 404's, 608's etc through 382, Telnyx and SIPRoutes. Bandwidth has been worse than the rest as they don't outright reject calls but they send a 100 trying and leave us hanging for 30 seconds. Peerless and one other carrier are completing the calls. Anyone know what makes T-Moble special that so many carriers will just 404 calls to their network?
TIA.
Dovid
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