Yes, every company does this. But be aware that they may extend your contract.
I have worked for two carriers (Verizon and Nextel) and we had to keep tabs on what the other carriers did as well.
I currently use Sprint (morphed into it as a former Nextel user). You can also call and get credits for dropped calls (your calls are charged up to the minute, not for a full minute, so if you make a 30 second call you're charged a minute. If the call drops and you have to call back but only for 5 seconds, that's another minute, as opposed to being charged once for a 35 second call).
Another thing to try is when your contract expires, let them know you're shopping around and see what they can offer you.
In general, the sales people will give you more perks because customer service in general is told to say "no".
In my experience, no company is better than another. You just have to find what one gets the best service in your area, or offers the plan that caters specifically to your needs. I've had a bad experience with TMobile outright refusing to credit something that happened because of their mistake (even they admitted the mistake), so be aware of that.
If you don't use your phone much, or aren't into contracts, just get a pre-paid cell phone. It can be cheaper.
