I rang up Orange, or should I say Orange India, to get a PAC code because I'm moving to o2. The lady in CS didn't seem to understand my question which was what happens to my existing SIM when I port my number? Do the numbers swap? ie. Does my o2 number become my Orange number when I give o2 my PAC?

Thanks in advance.

Your old SIM will become inactive. Or dead if you prefer.

I just moved my number from T-Mobile to O2. The T-Mobile SIM is now dead. The O2 SIM is fine. One thing to watch .... when I phoned in all the details, they said it would take a week to transfer. It did. What they didn't mention is until you call them again once it's complete it can't receive calls .....

When i ported to T-Mobile the T-Mobile number I was allocated was returned to the T-Mobile pool for them to use, and my Orange SIM is now dead.

You may find that during the transition outgoing calls on the new network start CIDing as you, but incoming calls will go to your old network.

OK, Thanks guys! I'll have to wait for a few days before ringing o2 so I use the last of my credit.