I have read in a number of Forums that a poor signal has not got anything to do with a SIM card.
I have two identical Nokia phones and two SIM cards on identical PAYG plans.
One phone kept giving no Network Coverage the other had at least 40% signal strength.
Swapping the SIM and the fault was on the other phone.
This identifies that the phones are OK and the SIM is responsible.
Cleaning the SIM card contacts made no difference and packing with a thin card to give better contact made no difference.
Putting in a new SIM card worked and both phones have the same signal strength which is not very good anyway where I live.
I do not understand the pedantic responses on forums saying that the SIM card is not responsible for signal strength when it clearly can be along with numerous other reasons.
Tags. SIM, SIMM, mobile phone, signal, weak, strength.