[VoiceOps] Issues to T-Mobile

Calvin E. calvine at gmail.com
Wed Jan 11 14:11:44 EST 2023

Check the 608 responses for a Call-Info header. If present, it should
contain a point of contact for redress.

"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.¶

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.



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
> _______________________________________________
> VoiceOps mailing list
> VoiceOps at voiceops.org
> https://puck.nether.net/mailman/listinfo/voiceops
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