How to obtain a Nano Sim to replace a Standard SIM and keep same phone number?

[Blackberry_9700]

Received a text from O2 because 2G & 3G being switched off soon.  Buying a new phone but also needs a new SIM because my old phone has a Standard Sim. I need to keep same phone number and credit to date on

my-pay-as-you-go tariff. Please advise.

[pgn]

Take the handset and current SIM into an O2 store, and any new handset you may have bought at a price cheaper than O2 store (usually) and they will help you change SIM, for new, migrate your number and any remaining credit to new and get you all set up.  Remember to take valid photo ID with you. Good luck, @Blackberry_9700 

[Enlli]

Have a look at this thread and the post from @M15.

It may just be a question of pushing out the correct size from the one you have

https://community.o2.co.uk/t5/Pay-Monthly/SIM-size/m-p/1404518#M215767

[pgn]

Transfer of number from old to new SIM and moving any credit balance in the same direction will need help from O2. From experience, in-store is better than battling through on the phone or Chat or Social Media, @Enlli and @Blackberry_9700 

Do take valid photo id with you, or you will be turned away.

[MI5]

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@Enlli wrote:

Have a look at this thread and the post from @M15.

It may just be a question of pushing out the correct size from the one you have

https://community.o2.co.uk/t5/Pay-Monthly/SIM-size/m-p/1404518#M215767

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This is the easiest way providing your sim isn't very old as no need to transfer anything at all to a new sim as you are still using your original one @Blackberry_9700