Most newer cellular telephones contain a computer chip called a SIM module.

They are easily taken in and out of the telephone.

My cellphone will pick up other countries networks. For example, my cellphone defaults to Vodaphone in Spain. But the cost for each call is incredibly expensive.

When our friends from Spain came to visit last Summer, we simply gave them the SIM module from my wife's phone. They put it in their phone, and they had cellular service in America.(We had a number of roll-over minutes)

When I go to Spain next September, I am going to buy a pre-paid SIM module and put it in my cellular telephone. Then I will will have cellphone coverage and service just like a Spaniard.