I wanted to detail my experience trying to set up the Mudita Kompakt with AT&T so that A) others don’t have to go through hours and days of debugging like I did, and B) the Mudita team understands that the Mudita Kompakt does not work with AT&T.
I’m in the US and I’m using a physical SIM that has been previously activated in an AT&T-supported phone (an iPhone), as suggested on these forums. When I initially transferred it to the Mudita, SMS and calls worked, but not mobile data. Then when I tried to transfer the SIM back to the iPhone, mobile data still didn’t work!
I tried everything I could think of to debug this, including the manually fiddling with APNs. Unfortunately AT&T has control over these, and will wipe whatever values in the APN you try to edit, so this doesn’t work.
Eventually I visited an AT&T store to get help. It turns out the moment you put the SIM into a device that is not supported by AT&T (i.e. the IMEI is not on the list of supported devices), it triggers certain automatic “blocks” on your account. I believe these can vary, but in my case it was a pretty self-explanatory “data block”. When you put the SIM into the Mudita, you’ll get a text from AT&T that the device is not supported, and in my experience this is exactly when the block activates (data works for the ~1 minute time period before that text arrives). This block sticks around until manually removed by an AT&T team member, so you can’t even revert to your old phone once this happens.
AT&T’s systems would not allow the store employee to remove the block while the SIM was in the Mudita. In order to remove it, we had to transfer the SIM back to the iPhone, remove the block, then transfer back to the Mudita. This didn’t even work the first time; it took two attempts, as the block auto-reactivated on the first attempt when the SIM was re-inserted into the Mudita. I’m still not sure why the second attempt “worked,” and neither was the AT&T employee!
I put “worked” in quotations here because this is clearly not a stable solution. As the AT&T employee informed me, if some sort of event triggers another configuration sync with AT&T, it is very likely the block will be reactivated. I’ll then have to go to a physical store to remove it, if it can be removed at all. Any number of events could trigger another sync; the obvious one is removing the SIM card and putting it back in the Mudita, but it could also happen for something as simple as a phone restart or entering a different country.
To the Mudita team: until such time as the device is officially registered with AT&T, I strongly suggest that you discontinue claiming that the Mudita Kompakt works with AT&T (and likely Verizon). Testing the communication bands is not sufficient here; AT&T actively blocks the device’s IMEI and there is no stable workaround. I suspect this issue will cause a lot of returns and greatly inhibit US sales of the device. This is sad to me because I love the device and think it is a unique and much-needed take on the dumb phone! Is there any plan to get the phone officially registered with major US carriers?