OK, still trying to get my 10 II to work reliably on T-Mobile in the USA where 4G is(mostly) required. I’ve made a little more progress understanding when it fails and kinda why.
Some background since I last was flailing around in July and August:
In addition to the Xperia, I’ve got a Pinephone running PMOS/Phosh (Edge). This device has Volte support in the modem hardware/firmware. I can pop the T-Mo SIM in the Pinephone and boot it up and it will connect to the network over 4G in a minute or two. It always gets registered, although there are a lot of dead zones for the device and it frequently loses LTE connectivity. Upgrades to the system software and the modem firmware have improved this, but not solved it completely. I wrote a short script to poll the modem manager software and notify me by playing an audio warning when this happens, so now I’ve got a pretty good idea of where the poor reception areas are and when I’m offline. This has helped in further diagnosing the SFOS/Xperia issues . . .
OK, back to the Xperia. Just putting the SIM in the Xperia 10 II doesn’t work. It won’t register with T-Mobile. What I can do is put the SIM in the Pinephone, wait for it to register, then pull out the SIM and pop it immediately into the running – and preferably recently rebooted – Xperia. Now the 10 II will register on the T-Mo network and can be used. This is good until I take the phone somewhere that the Pinephone would lose its LTE connection. The Xperia drops off the network too, but unlike the Pinephone, it doesn’t reconnect when service is restored. Rather, network status becomes: “Denied”.
The reboot, put the SIM in Pinephone, wait for service, then swap SIM back to Xperia procedure usually works to get service back on the Xperia, but this isn’t really practical when out and about to carry 2 phones just so I can swap the SIMs twice to restore service. Also, I don’t know when the service drops on the Xperia, so I can be incommunicado unawares for quite a while.
I post this to see if anyone’s got other ideas, and for anyone in this situation to see if their issues are similar. I’d also like to know if anyone knows a method to check the modem status in SFOS from the command line which I could check occasionally to notify me when the modem gets denied. I’d also also like to know if anybody’s got any suggestions on how to get the Xperia to get un-denied without the SIM switcheroo trick.