Just a tip, if you find yourself in a location that you'll be staying at for awhile and that has a low signal try this,
Update your PRL (Preferred Roaming List). It's a set of instructions that your phone uses that contain cell services for a given area . Go to "Settings -> About Phone -> System Updates -> Update PRL
I'm bringing this up because I've seen a few posters mention that at work or at so and so, their batteries seem to drain faster. It could be that the phone is increasing it's power to transmit and receive with towers that are further away due to it not knowing that closer ones are at hand.
Here is some more detailed info...
http://www.justalurker.com/howto.html
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PRL
(Preferred Roaming List)
The PRL is a list of information that resides in the memory of a digital phone. It lists the frequency bands the phone can use in various parts of the country. (The smaller bands within Cellular or PCS, technically called blocks.)
The part of the list for each area is ordered by the bands the phone should try to use first. Therefore it's a kind of priority list for which towers the phone should use.
For example, say you had a Sprint PCS phone, and were travelling in an area with no Sprint coverage, weak Verizon coverage, and strong Qwest coverage. The PRL would tell the phone to look for towers using Sprint's band for that area. Finding none, it might tell the phone to search for towers in Verizon's band next, perhaps because Sprint's roaming agreement with Qwest was not as favorable, or none existed. The phone would use Verizon's towers, as dictated by the PRL, even though Qwest might provide a better signal.
Since a PRL tells the phone "where" to search for a signal, as carrier networks change over time, an updated PRL may be required for a phone to "see" all of the coverage that it should.
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So try updating your PRL, and if successful your phone will do less hunting for a good signal and this may help in keeping your battery from being drained faster.
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At my own work, I use the phone thru out the day to stream music. Since today I've received fairly bad reception, so I updated the PRL. What a world of difference! Right at my cubical I'm now getting 4-5 bars, and a solid data connection.
Finally, some neat reading:
http://electronics.howstuffworks.com/cell-phone.htm