Getting a "sim not provisioned mm#2" message on Galaxy S3

You need to replace the phone. It will not be allowed on any other service provider.  T mobile kicked non VoLTE phones off in January.  The oldest galaxy allowed on Verizon, T-Mobile and AT&T is the S5.  

Your phone is from 2012, it is not voice over LTE capable, and you should have received a message that had to be replaced. I suspect that it has been suspended until you do so.  

   Pretty much anything that you purchase off of the prepaid rack is going to be better and faster than the old S3.  

Well thanks - I guess I'll find a new service.

Let's look into why you're receiving that message, @mpgrahek, and what action you can take to resolve it!

We want to advise that, as @lizdance40 already stated, AT&T plans to end service on 3G/3G HSPA+ wireless networks. This action will take effect on February 2022 which will enable our network to better accommodate next generation technologies and services.

Customers still using a 3G dependent device (including non-HD LTE devices) are encouraged to move to newer devices to ensure the best possible experience. 4G and 5G devices use newer, stronger network connections that improve bandwidth, provide better audio and video quality and a better overall experience.

For a list of which devices that will function beyond the scheduled date above we invite you to check out our list of devices that will work once 3G goes away. It's even possible to shop for prepaid phones that support LTE and 5G coverage. 

Also, AT&T isn't the only service provider retiring 3G. Verizon, and T-Mobile will all eventually shut down their 3G networks, so any 3G dependent devices will no longer work on the networks of these carriers.

Give this a try and let us know how it helps. We hope you find this info useful!

Lar, AT&T Community Specialist