I'm consistently amazed by how much power the telecom companies have in the US. I'm living in China, where they use SIM cards, and I just bought my phone and a

I'm consistently amazed by how much power the telecom companies have in the US. I'm living in China, where they use SIM cards, and I just bought my phone and accompanying phone number completely anonymously, using cash only. When I recharge the money on my card, I go to a store and pay cash. If I want a new handset, I just take out the card and swap it into a new phone - keeping my cell phone number and contacts. The flexibility has even fueled a boom of tiny cell-phone designing companies that make all kinds of innovative creations called 'shanzhai' phones. Is this just a US thing? Or are handsets locked to carriers in most of the rest of the world as well?