I had an existing line with XM. I had a separate phone number. I ported that number to XM to replace my current number.
Since replacing my phone number, I have no Voice mail, no wifi calling, no Volte.
I've reset my device to factory fresh defaults - and still no help. I called and chatted - and was told to wait a few days and call back later???
Seems like something isn't setup properly on my account. I've gone through all the settings 1,000 times. Googled for hours, Cant find a solution, has to be with XM.
This is on a galaxy s9.
After any reset to defaults there are going to be some OS and 'roaming info' type of updates needed. Do all that stuff as much as possible before investigating further. Also you may have to deinstall and reinstall the NPN/whatever-three-letter-acronym thing that maps the SIM to carrier and/or vice versa - especially if the phone number is also hashed into that identity key three-letter-aconym thang.