I'm not 100% sure, but I don't think so, could you just set up a call forwarding from your old number to your new?
This is a good idea. I guess I could transfer my old number to a pay as you go SIM and set-up call forwarding, then just never put the SIM into a phone.
Good idea, thanks.
Now I just need to find out if O2 will be up for me swapping numbers around. Carriers are never very helpful in this area...
You need to be aware that you will be charged for all calls forwarded from your PAYG sim to your new number at whatever your standard call rate from the sim is.
So you will need to make sure that the sim is kept topped up to meet those charges.