I'm not a communications engineer but I've read up on cellular telephone technology.

The first priority is signal strength. This is only logical.

The second priority is first-come-first-served, in a manner of speaking. Whichever tower was first with contact, stays in contact until the signal strength rule takes over. So if you're within one tower's sector and start to move into another tower's sector, the first tower stays with you until the signal strength from the second tower becomes greater than the first.

There is one more aspect of some cell phone company towers. That is signal quaility. On my cell phone I can (with help from my son LOL) toggle from "tower-signal strength-signal quaility. By knowing this I was able to call my cell company and tell them what was real time at my home and they did a drive by to verify and then tweaked a tower to better "hit my home"

Mike

Keeping your Rule #1 in mind, can you share how that toggle feature works? I'd like to be able to convince the cell company to tweak the tower nearest our house. We get improving signal strength (over none at all indoors) from the front yard (marginal) to a couple of blocks up the street (full strength), and it doesn't matter which direction you go.

Well my phone system is Nextel/Sprint so if you have that system I will jot down the sequence if not go into the nearest Corporate store or service center for your system and they should be able to show you. Another good way is to call you 611 number or what ever your tech/customer support number is, but do it late at night so they are not in a rush.

Mike

No, I use Cingular...I mean AT&T...or whatever it is this week. I'll check with the nearest customer call center for procedures...

You can use the methods at this site, depending on your phone. Each manufacturer does it a bit differently. In fact, it may vary in the same model with different providers.

http://www.wpsantennas.com/pdf/testmode/FieldTestModes.pdf

Vulcan is correct in saying that signal strength is the first criteria and signal quality is the next criteria. A third factor, which only rarely comes into play, is the load on the tower. If a tower is handling all the subscribers it can, the mobile device should try to register with another nearby tower. The technology in use, CDMA, GSM or whatever, will determine the algorithms used for this and how it actually works.

Keep in mind that looking at signal strength and signal quality is only applicable for the exact location and the exact time you are checking them. If you are moving -- even short distances -- or checking periodically over time, expect to see fluctuations in the measurements.