Sorry if I am being thick, but I can't find the answer on the website. I want a cheapish pay-as-you-go mobile for my son, as he is starting to do things on his own after school etc. Tesco have some decent deals at the moment, but I can't find anything that says whether or not the airtime vouchers expire. My wife has a Virgin mobile which she tops up as and when necessary, but the credit never expires. I am aware that some companies require you to top up every month or lose the credit, which is no use to us. If anyone knows what happens with the Tescos airtime vouchers I'd appreciate it.