Bought a new phone

[JABrice]

Do I have to go through the sim swap business again

[MI5]

@JABrice 

If you upgraded you can use your old sim.

If you just bought a new phone, use your old sim.

If you took a new contract elsewhere, you need to migrate your old number Guide: Migration & porting into O2  

[jonsie]

Just use your old sim, everything is automatically done for the new tariff

However, if you haven't had a new sim recently (could be a 4G sim) and you have bought a 5G phone and are in a 5G area then a sim swap is advisable

[Oxonian]

If a SIM swap is required as suggested by @jonsie, you can do this by visiting your local O2 retail store :-

Store locator | O2 UK | Find Your Nearest O2 Store

https://stores.o2.co.uk/

Please take photographic identification (photo ID) with you.