When I traveled to Australia over Christmas with my mum, though we understood that cellphone calls overseas would start to rack up an impressive bill, we neglected to realize that SMS messages would incur a similarly hefty charge, being billed at something like $0.75 per message, including both incoming and outgoing messages. By the time we returned to the states, we’d sent and received enough text messages to generate a whopping bill from T-Mobile. So when Alex and I went to London last week, I figured out a solution: use my unlocked iPhone in the UK by purchasing a domestic pay-as-you-go SIM card, pop it in, and I’d be good to go. Instead of hundreds of dollars in call and SMS charges applied to my T-Mobile bill upon my return, I paid £10 for the SIM card and £10 for call credit, and that was more than enough to last a nine-day trip full of SMS messaging and calls.
Interestingly, I didn’t have to register with O2 in any way at all, I simply plunked down a £20 note and got, in return, a UK telephone number; the transaction took roughly two minutes. Thanks to the excellent ZiPhone software, all I needed to do was exchange my T-Mobile SIM card for the O2 one, and I was away. There was an über-nerdy moment where I exchanged SIM cards on the street, using one of Alex’s earrings to pop out the SIM door on my iPhone.
It’s fairly easy to see why US carriers are scared of SIM-unlocking; their International business, in particular, stands to suffer when consumers are free to choose their own carrier on-the-fly when traveling. It appears not to make a great deal of sense from a customer-retention standpoint, either. Since most US cellular customers pay on a monthly contractual basis, not allowing them to use their GSM phone with another carrier if they wish seems foolish, since they are already obligated to continue paying their bill until the end of their contract. In the US, this is only really applicable to T-Mobile and AT&T, the only two networks that operate a GSM-compatible network. Still, I think it would be healthy for competition if both networks and their hardware vendors allowed open access to phone handsets.