Sim not working

[#1]

I have just tried it in another phone, it says no service again

[#2]

@murat1301
The other sim that you tried in your phone, is it an active sim? Is it from another network?

[#3]

Yes it is an active 3 network sim that was previously being used in the phone until today when i changed to giffgaff, the giffgaff sim worked for about 40mins then said no service. From that point both sim cards have stopped workinng in the phone