Unlocked iPhone 4 SIM Switching On The Fly

If I buy an unlocked iPhone 4, and I travel with it and no laptop, will it let me switch SIM cards on the fly without reconnecting to iTunes every time I switch?

What exactly does the iPhone want to connect to iTunes for anyway? Apple's support doesn't actually seem to know and my theory is just for APN and carrier-specific settings which I would be able to find and set on the own if the phone lets me.

Anyone know for sure though?

Thanks

There's no restriction on switching SIM cards with an unlocked iPhone. (just like any other cell phone in that respect) You don't need iTunes for that.

You do need iTunes for syncing, purchasing apps, updates, etc.

Regards.

I am well aware of how normal unlocked phones work, however, Apple's Website states that you can:

Get a compatible SIM (iPhone 3GS) or micro-SIM card (iPhone 4) and select a plan from the carrier of your choice. Then insert the card and set up your iPhone using iTunes on your Mac or PC. With a few clicks, you can start making calls.

Source: iPhone 4 & iPhone 3GS - Apple Store (Canada)

Not sure if there's anything different about the iP4, but my 3G doesn't require Jack in order to switch the SIM and start making calls on the new network. Just 30 seconds to detect the new cell tower and that's it. Using a pre-paid T-Mobile SIM right now. (boy Tmobile stinks)

I haven't touched iTunes for ages, btw.

Doug

Doug, being with T-Mobile, I'm assuming you're from the US which means you can neither buy an unlocked iPhone nor have AT&T unlock it for you. So, I'm assuming your jailbroke it in order to switch SIMs?

I just want to buy one unlocked (Apple sells it unlocked in Canada, and the rest of the world except for the United States for that matter, and I don't want to deal with the hassle of jailbreaking, I just want to buy it, stick my SIM in it and when I travel, swap SIMs without reconnecting to iTunes like Apple's site implies I have to.

Has anyone here used an officially unlocked iPhone and switched carriers?

well like the have mentioned already you don't need itunes if the phone is already unlock, however i don't know how common are the new micro sims in other countries for you to be easily swapping sims