[RyJones]

T-Mobile consists of at least five distinct networks depending on when your carrier was purchased, last time I was talking with some of the network security guys in Factoria. It’s been four years - they may have converged some of them.

[Melatonic]

Also failing here in the Los Angeles area. Used to be on Sprint before the acquisition. Probably location dependent

[asveikau]

I got the failure message in San Francisco.

Not sure if it makes a difference, but I had a T-Mobile SIM card I bought in Seattle in 2010 and was carrying from phone to phone for years, but I recently replaced the SIM because I heard newer t-mobile SIMs can do better finding 5g coverage.