Well, I think what he's saying about switching towers is misunderstood.
I have verizon as my wireless provider. I live in a small town, about 20 miles from a much bigger town. I do not have a verizon tower in or around my small town so when I come home there are times that I have one bar on my phone. When I make a phone call sometimes peoples voices go in and out and I can't understand them. Many times the call is dropped before it can switch towers.
Verizon, like many other carriers want you to use THEIR towers first, and then if there isn't signal it will switch over a different carriers tower. In my case, there are days I do not get ANY verizon signal at all at my home. On these days, I'm the happiest as there is an AT&T tower just up the hill from me. On these days, when verizon doesn't get signal to me, it switches to AT&T and I get full bars (YES!) This is what I believe the original poster is trying to say. I believe the term he is referring to is called "Jailbreaking" a phone, not positive but I have heard many people talk about it. Basically, what it does it picks the tower, regardless of carrier with the strongest signal. Most carriers put some type of programming in phones to use THEIR service first, almost at all costs. I have often wondered if someone could hack my phone and change the signal changes so that if it doesn't have two bars from verizon it would switch to the AT&T tower.
I have figured a way to do it manually. I cover my phone completely when there is only ONE bar on it from verizon. I wait until it connects to the AT&T tower (full bars) and make my call. After connection, I then uncover my phone and talk, blue tooth makes this very easy for me.