sim card vs phone virus? which is the issue?

[Android Central Question]

phone was working fine until it showed " emergency services' mode the entire night. unable to ph and txt signals.

tried:
aeroplane mode- didn't change
restart/ shut down phone= did not work.
took out/in my sim card from phone= did not work.

found out via testing:
1. my sim + phone= not working.
2. my sim + another phone= working
3. my phone + someone else's sim= working.

is this a sim card issue or a virus on the phone? which do I change?
any help would be much appreciated. thanks

 

[thisbearisdrunk]

so someone's sim means different operator or the same?