I have had a pay monthly account on O2 since 1999 and my last upgrade was a couple of years ago when I got the O2 XDA Stellar (a rebranded HTC Tytn II) running Win Mobile which was a fully featured and expensive mobile at the time...I paid O2 £49.00 towards the phone and was put on their Online 35 plan for 24 months with 800 mins (I only use on average about 20-30 mins per month), 1000 Texts, unlimited O2 to O2 etc but only 1mb inclusive web browsing...They gave me a loyalty discount of £10 per month.
My contract is up for renewal on 24th Nov but I can get an upgrade 1 month early...next week to be precise.
I now want a mobile on unlimited internet and a bigger screen but the thing is I'm not overly excited by O2s range of pay monthly mobiles...I had thought about an iPhone 3GS but I've got an iPod Touch 32gb 2G upgraded to the latest firmware which is an iPhone without the phone part and

I'm not as excited about the iPhone as I should be...it's overpriced and I don't like it's lack of multi tasking.
I know O2 will have the HTC HD2 soon and I was keen to see this in the flesh and read a few reviews when it comes out but I think it's release has been put back a few weeks and anyway if it was running Android and not Win mobile I may have waited.
I had a play with a friends HTC Hero and I'm impressed however it isn't available from O2...and reading some comments on the O2 Forum they're not renewing the loyalty discounts at the moment...that plus the fact that there's no O2 3G where I live is swaying me towards a Hero on Vodaphone which has pretty good 3G around Central Scotland...now to my question

...
If I get a Hero now on a Vodaphone contract with a new Sim/Phone no...can I use it with the new Sim until my O2 contract ends and then port my O2 number over to Vodaphone when my O2 contract ends in November?
Or can my existing number only be ported over at the time I get the new phone/contract from Vodaphone?
Thanks,
John.