I've just ordered a new phone with an O2 sim. I want to go on the O2 Simplicity price plan, and so I ordered a Simplicity SIM and it says it will take about 2 weeks to arrive.

My phone should arrive Monday, and I don't really want to wait 2 weeks to be able to use it properly.

My question is, can I put the existing SIM that comes with the phone onto the Simplicity tariff?

Nope, Simplicity sim cards exist only as Simplicity sim cards.

Yes, if its a PAYG card you certainly can use the simplicity plan, I do. Put in £10 or £15 whatever and phone and its done instantly.

Conflicting information.

I'm talking about the monthly contract which you pay for every 30 days via debit, but it's not a proper contract.

You can use PAYG Simplicity on a PAYG sim card, but not pay monthly. They will send out a new sim card.

If you ever cancel Simplicity pay monthly, they will send you a PAYG sim.

I phoned O2 customer services to ask them the best way to switch to Simplicity Pay Monthly (from O2 PAYG) and they told me to call in to my local O2 shop. It took about 20 minutes to get it sorted and I left with the SIM ready to put it in my phone when the PAYG SIM died. About an hour later I was officially on the Pay Monthly Simplicity tariff.

Having signed a contract instore I think that it is technically a proper contract.