Please help me get my phone call service working again mine says SOS

It has been reported across all news outlets. AT&T is having a network issue and also affects any provider that uses their networks. Users are starting to come back online, but have not seen a timetable on when full service will be restored. You can see this at Downdetector.

https://downdetector.com/status/att/

Large-scale cellular phone outage hits users across the US

The Guardian

More than 50000 affected as users of AT&T, Verizon, T-Mobile and UScellular report disruptions including to emergency service calls.

Read any of the many other threads already posted about this, right here in this forum.