Do you have other instances of calls or texts not going through? I ask because I had that problem, and it turned out the TMobile towers often take longer to find my phone number (the number itself - this issue persisted through multiple physical phones) than the default 15 second timeout to voicemail. I found instructions on the TMobile forums of how to increase the timeout period, bumped it up to 25 seconds, and haven’t had an issue since.
Do you have other instances of calls or texts not going through? I ask because I had that problem, and it turned out the TMobile towers often take longer to find my phone number (the number itself - this issue persisted through multiple physical phones) than the default 15 second timeout to voicemail. I found instructions on the TMobile forums of how to increase the timeout period, bumped it up to 25 seconds, and haven’t had an issue since.