The latest run of XB3M1's won't associate with my cellular network.

‘AI’ fails: 0x25. The provider can see the modem/SIM and can’t explain why it won’t connect. My older, (pre-recall) modem connects to the network just fine.

NB-IoT only
APN verified correct
RSSI low but usable
FW ver 11411
Provider ‘Ting’ (T-Mobile Network)
Remote Manager disabled

I use Ting as my cellular service provider, and I’m not sure if they support the CAT-M protocol.

What are the part numbers of your new units vs old units?

The Digi p/n is XB3-C-A2-UT-001. The Digi XBee3 LTE-M/NB-IoT p/n didn’t change when Digi recalled all units to flash the U-blox internal cellular modem. Original firmware: L0.0.00.00.05.06 [Feb 032018 13:00:41] new firmware: L0.0.00.00.05.06,A.02.00

I’m having a difficult time determining with 100% certainty if the problem lays with the new XB3-C-A2-UT-001, or on Ting’s end ‘possibly not enabling NB-IoT for the sim card’. My only reference is my original development XB3-C-A2-UT-001 and a Ting sim that activated and communicated NB-IoT TCP without a problem. Unfortunately, the original modem/sim has been shipped across the country to a customer site, and I can’t compare it for reference.