Oh man, AT&T might be rotten, but Verizon is actively evil when it comes to this. Like cackling Emperor Palpatine levels of evil.
They heavily modify the software running on the phones they sell, and they don't allow any others on their network.
Modifications include:
* Shoving their logo into every orifice
* Leasing you access to the GPS chip in your phone (or even the E911 data)
* disabling all file transfer methods to try to get you to pay for MMS
* disabling native Exchange support to upsell you to enterprise bullshit
* blocking any media content that doesn't come through their bizdev
* Still pushing motherfucking WAP (Gopher over telegram, I tell you)
I have a Blackberry 8830 on Verizon. I'm loathe to switch carriers or phones.
The customer service is pretty great. I have access to the GPS. I've been able to get media on and off the phone as necessary. It has unlimited network connectivity and tethering.
I'm not convinced they're any worse than any other carrier.
Most of the asia carriers would compete over their services(no carrier-locked phone). But, in US, it seems like most of the carriers are competing over what phones they can provide.
Sort of. The GSM providers don't know/care if you use a random GSM phone on their network. Of course, if you rent their GSM phone, they are not going to let you use it on a different GSM network.
(People seem to want free phones, and then seem confused when the person that gave you the free phone doesn't want you to use it on the competitor's network. If you buy your own phone, you can use it wherever you want.)
They heavily modify the software running on the phones they sell, and they don't allow any others on their network.