The number is on the do-not-call list

Your organization listed this number as one its agents must never ring — somebody asked not to be called, or your own system said so.

What to do

Do not call it. If that has changed, remove it from the list — DELETE /v1/do-not-call/{number} or the console's Telephony page — and place the call again.

Retrying

No: the same request gets the same answer until something is changed.