My old BT Cellnet 'u' phone has stopped working. Help!

[matthew_o50]

Hi, i've had one of those old Philips c12 BT cellnet 'u' phones for a few years now and up until last week it was working fine. I use it to send text messages from arboad as it only costs 5p and I used it at easter from the Republic of Ireland and it worked fine. I make sure I make a call on it every so often to keep it active but last week I turned it on and IMSI Failed has came up on the screen. Whenever I call it, it says that the number is not recognised. Has anyone got any idea what could be wrong? I had about £8 credit on it. I'll be completely gutted if it's broke because it had one of the best tariffs ever.

 

[matthew_o50]

I'll give o2 a ring when I get a chance. I don't think it's a problem with the phone, more the sim as the number is not recognised when I dial it. Personally I hate the phone but the 5p text messages from abroad are amazing. I'll be completely lost without it. The 'u' sim cards and the phones are paired together so you can't use a different sim in the phone or use the sim in a different phone.