T-Mobile registration trouble (USA)

[Bruce Johnson]

After something of a hiatus induced by work priorities, I am back to my 
project that uses ModemManager and a "glue" program to tell it to 
connect. Code that was working back in July isn't working, and our IT 
folks gave us new SIMs from T-Mobile. Here in the USA, T-Mobile has 
instituted a requirement that a SIM be bound to a specific IMEI. I am 
using the ModemSimple.connect call to connect, and I keep getting a timeout.

Using mmcli, I run this command and also get a timeout:

$ mmcli -m 0 --simple-connect='apn=fast.t-mobile.com,ip-type=ipv4v6'

My boss is getting the same thing with a different modem and SIM. Both 
SIMs have allegedly been paired with the IMEI in T-Mobile's records.

Does anyone know if simple-connect still works with T-Mobile in the USA?

Thanks!

-- 
Bruce Johnson
Chantilly, Virginia
USA