I'm not sure if this has come up here before, I couldn't find anything specific, but I'm seeing an issue where calls originating from T-Mobile to other carriers are not generating ringback. The call is indeed ringing on the other end, but on the T-Mobile phone, it's just dead air until the person on the other end answers the call. It's not all calls, but it is reproducible to certain phone numbers and reproducible using various T-Mobile customers. It's not limited to a single phone T-Mobile number/customer. Further troubleshooting has shown that calls from other providers (ie AT&T, Verizon Wireless) do not have this problem to the same numbers the issue can be reproduced from T-Mobile. It's only calls from T-Mobile numbers to other phone numbers outside of T-Mobile so far. The no ringback issue seems to occur whether you're on wifi calling or on a cell tower. All of the T-Mobile users we can reproduce the issue with are in Southern California. Not sure if any of this matters. I tried to deal with customer service and opened a ticket that supposedly was escalated to engineering, but of course that fell on deaf ears and the response I got was basically "Can't reproduce, it's not our problem" 8-/ ... Any T-Mobile engineers on this list that could help or any recommendations on how to raise attention to this problem to someone at T-Mobile with a clue? Gabe