US Carrier Call Blocking

Telnyx has become aware that major carriers in the US industry are actively blocking calls to their subscribers devices due to them deeming the calls as potentially fraudulent.

We are seeing, that high volume calls from non-rotated caller IDs are experiencing a higher amount of user busy responses in the form of a SIP 480/486 Busy Here.

In some cases, it's also being reported that the carriers of the destinations are using services that are categorizing calls as "Potential Spam" on the user's devices.

How to use Whitelisting

We also understand that there are many valid & legitimate use cases, where there is a necessity for high volume calls (e.g. alerts, appointment reminders, etc.)

Telnyx recommends that our customers actively submit a whitelisting request to the major carriers, in order to disclose your use case and in turn prevent your outbound calls from being blocked. Please see the below websites where you can submit these requests.


We are committed to combating spoofing and illegal robocalling through implementing the industry-wide STIR/SHAKEN solution, in an effort to play our part in reducing these illegal occurrences. You can read more about our three-part articles where we discuss the implementation in detail.

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