Hey Manny - My wife and I also recently switched to XM and are also having the same issue that you mentioned above. There is a pretty extensive forum on the Comcast support site dedicated to this issue and a lot of frustrated people.
I have noticed that the dropped calls issue only happens when I am on wifi with wifi calling turned on. Incoming calls will drop almost immediately afterI answer them and then I will have to call back the person or wait for them to call me back. This generally does not happen on cellular, but only when I am on on wifi with wifi calling enabled.
I have been messaging directly with an Xfinity support person and providing call logs and other data to help the XM engineers address the issue. This issue also appears to be isolated to only iPhones. Android devices are not having this problem. Also, during my communications with XM support, they indicated that they are a relatively small team and they are having trouble getting in touch with Apple Tech support to address the issue, so I am hoping this forum can highlight the issue and we can get a fix. These smaller, "virtual" providers like XM that lease from other providers towers have smaller programming staff and do not have the programming staff and natural connection to Apple like other providers. Hopefully highlighting the issue will help. Please feel free to highlight this forum to others and highlight the issue to Apple Tech support so they can engage with XM.
XFINITY Mobile Dropped Calls
