I would just like to thank all who kindly responded to my question. I am with Tesco, and had lost all my credit, twice. Some of you will know that I am not at all tech savvy, so when it happened once, I thought I had left my phone on, and it just 'dribbled' away! After the second top up, and I know it wasn't a lot, £10.00, disappeared as well, I got cross and thought I would change provider. Paid a visit to Carphone Warehouse, where Tracy said that something called Roaming was switched on. What is that? Anyway she swithched me off. Also I didn't know about unlocking, I do now, although, I still haven't managed to do it. Several on line chats with far away folk, then I paid a visit to the mobile phone shop in a big Tesco store. Ayrton was extremely helpful, and tried to do the unlocking for me. The code provided wasn't doing it's stuff. I was left with the message that the ethereal someone, would get back to me after checking with Nokia. Did he? did he heck. So this morning I had another on line chat. I have discovered that my calls are charged at 8p per minute??? That doesn't seem too bad, so I am still with Tesco network, at the moment. If I have any more problems, you may hear about them.?