Using an iPhone with different SIMs

Can one use an iPhone on a pay-as-you-go basis in UK, France and Germany by inserting SIM cards relevant to the country in question?

M

Which iPhone are referring to? If it's a GSM iPhone, yes. Here's an article that I copied from about traveling in Europe that will help if you have a Verizon iPhone:

The most significant Global Phones for Verizon and Sprint are the iPhone 4S and new iPhone 5: the first Apple iPhones that work on both CDMA and GSM networks. Verizon iPhone 4 (not 4S) customers are out of luck — both are CDMA-only and will not work in Europe. This means that if you’re on Verizon or Sprint and you have iPhone 4S or 5, you can use your phone in Europe and get 3G and regular GSM coverage.

Thanks for the information. I'm really only interested in European travel and presume that I therefore need 3G and GSM. I'm something of a novice regarding phones but have an idea that it's more expensive to buy an "open" i-Phone - one that is not blocked by a provider. This must be on the basis that providers sell blocked phones more cheaply because they know they will get money back from usage. From this, I suppose that I-phones sold by Apple are "open" and therefore accept pay-as-you-go SIMs in various countries, whereas phones sold by, say, Orange, will be blocked.
M

That's probably correct (I don't know Orange's policies but I'd guess you're right). You can buy an iPhone direct from Apple for an unsubsidised price, or SOME carriers will unlock a carrier-locked iPhone if you've been a customer of theirs for a while and are now off-contract. In the US at the moment this is the ONLY way to legally get an unlocked phone. Other countries have different laws on this topic but this forum follows US law.

You can often find used unlocked iPhones through services such as Craigslist, but be very cautious and have your own SIM for testing.