So I got a new phone for my birthday, but the sim card from my old phone is too big. I've tried googling it but I don't understand what to do. I'm with tesco, sim only. Do I go to tesco and buy a new sim, but how do I keep my number and contacts. Am going on hol on Sat and wanted to use the new phone for google maps and stuff like that cos it's better. I suppose I could bring the old phone and use it as a mobile hotspot. Oh lord my brain is fried. Can anyone explain in simple terms