my husband has just purchased a new mobile as he couldnt see the numbers on his old one. He put the sim c ard from the old one in and it is showing "Sim card blocked". Being 80 and a technophobe needs some help. Please give us some advice in layman;s language.
Most phones are locked to a particular network, meaning, for example, that if you buy a phone from O2 it will only work with an O2 SIM card.
I would guess that you have bought a phone that is locked to a network different to your SIM card.
Most phones can be unlocked for a small charge though, take it to the stall on your local market that sells all the phone accessories and ask them about it.