[bifftannen]

You can't take a unlocked GSM phone onto Verizon or Sprint. You can't take a Verizon phone onto Sprint. You can't take a Sprint phone onto Verizon.

The only carrier you can choose with GSM is T-Mobile. But wait, they use the 1900MHz 3G band, so if you've got a phone that doesn't use that band, you're stuck with EDGE data.

LTE won't change this, they've chosen different bands.

[aneth4]

You can however sell your phone and buy one for a different network. iPhones in particularly have a very high resale value, and regardless the phone you bought maintains its market value and is resalable.

Telecom networks are extremely expensive to build. Having more than a few on the same technology would be wasteful, and consumers benefit from a diversity of technologies in the long run in addition to some level of network compatibility.

But seriously, don't like your network? Sell your phone on eBay and buy a different one that works on a different network. How hard is that?