Nighthawk MR1100 Registration Error

[hmbanner]

I purchased the MR1100 ATT hotspot and received an unlock code from ATT to use with a T-mobile SIM.

It’s been working great for three weeks but now attwifimanager pops up saying Mobile Broadband Disconnected and giving a Registration Error - Phone not allowed - MM#6.

I did a factory reset but was not prompted again to enter the unlock code. I see nowhere else to enter the unlock code again so I don’t know how to get past this error.

Please help!

[JohnPeng]

The error code means that T-Mo is blocking its service to your AT&T M1100. 

Thanks

[OffroadGirl]

Did you get this figured out?  I also have an unlock code but no way to enter it.