HELP I'm getting "sim not allowed MM #3" error when travelling to Canada

pointbob

    I've been using the same sim card for a few years with Tmobile (same ZTE android 5.1 phone).  And about 2 weeks ago (I work in Canada crossing the US border often) I started getting a "sim not allowed MM #3" error message on my unlocked phone. This results in no phone/ network service whatsoever.

     

    I pulled the sim card out, wiped it and restarted. It worked ok for a day or so and the problem is back. I cannot go for more then 4 or 5 hrs with the error message coming back (while in Canada). Or I simply get a message saying "no service". If I try to re-connect to the mobile network my sim just refuses to do so.

     

    As a fix I have to do a reboot of the phone to get reconnected to the canadian network that tmobile partners with here (telus). Also I check the APN number and reset that to default so no issues there. The IMEI/ESN is not on any blacklists...besides I've had the phone for a few years as I said.

     

    I've got lots of credit and Tmobile plan does not expire until Oct 2018.

     

    Can someone offer some help?

     

    Thanks

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