suddenly my phone no. has disappeard

Can anyone help? I've been a customer for nearly years, automatically paying monthly, with the same phone number. Suddenly smarty doesn't recognise the number. I've asked for and received a replacemend SIM, in case it was that. I put the new one in and saw "emergency calls only". I've tried the SIM in an old phone (that does still work) and got the same problem. Is this because smarty has been brought up to Vodaphone? How can I get the number working again?