here are the rules for pay as you go on orange
We will disconnect your Device if during the previous six months, you have not Registered a new Top Up or you have not made chargeable calls from your Device or received incoming calls on your phone. For the avoidance of doubt calls shall include but not be limited to voice calls, data calls and text messaging. On disconnection your mobile telephone number will be reassigned. On Re-connection you will be assigned a new mobile telephone number. Orange may at its discretion, on request and on Re-connection to the Services, re-credit the amount remaining on your account at the time it was disconnected.