Old sims being swapped

[JonnoBean]

I am using a SIM that is over 20 years old.  It is one that O2 wants me to swap for a new type.

My SIM is PAYG and currently I only need to my phone occasionally or top up to keep the account.

When I swap my SIM will the current contract remain the same or will I be forced to switch to different PAYG account that requires me to pay £XX per month? 

[Enlli]

As far as we know everything stays the same although I wouldn't put it past O2 to try and upsell.

Best going into a  O2 store with photo ID to swap

[pgn]

It should all remain as-is, @JonnoBean - all that changes is your 2G SIM gets exchanged for a newer 4G one - same number, same terms, same "tariff", so long as they don't get you to undertake the hard-sell (VMO2 incentivizes their staff to sell contracts). Good luck, @JonnoBean - don't forget to take some photo id when you go to the O2 Shop!