A use for all the O2 SIMS everyone seems to grab everytime they come up You can get upto £50 but I only got a fiver - not bad for 2 mins work though
Step 1 - Get new sim card.
Step 2 - Send an SMS from existing handset with existing SIM Card to 865555 with the Mobile Phone Number that came with your new SIM Card (e.g. 07999 123 456) as the message.
Step 3 - O2 will send back a message confirming your upgrade and your free calltime credit amount.
Step 4 - The calltime credit will be applied to your calltime balance in 14 days. The new SIM card and new mobile phone number will be disconnected.
Step 5 - You can now use your new handset whilst retaining your existing number, calltime balance, Bolt Ons and any numbers stored on your SIM card.
Step 6 - Once calltime credit has been applied, bin the new SIM Card
Acknowledgements: MSE People have confirmed this works on here
Credit to charliethirtytwo:
The process now seems to be-
1. Call 5450 from your existing no. & handset
2. They give you an authorisation no. & let you know how much you'll be due
as credit to your EXISTING no.
3. Put your new(free?) sim card into your phone & dial the same no. using
this 'new' sim (for free)
4.They will then ask for auth code (given on the original call), your EXISTING
phone no.,your name, your postcode & house number.
5. They then confirm the amount to be credited in 14 days & advise that the
NEW/FREE SIM CARD no. will be disconnected straight away (so if you
have free or bought credit on this card then USE IT!!!!)