I have been in the Cell phone Business for 17 years and most of that time was on the technical end in repair and installation. I am a level two factory authorized repair tech for Motorola, Nokia, Ericsson and some older Audivox products and Phillips.
Here is a few facts and a little education on wireless phones.
Analog Cellular is licensed (the stuff they were moving away from 10 years ago). is licensed at 3 watts on non
hand held devices.
TDMA (Cingular) and CDMA (Verizon and sprint) are licensed to 1.2 watts on hand held but usually no more then .6 watt.
GSM (Cingular and Nextsmell and a couple other PCS carriers) are max 1.2 watts total on hand helds but again .6watt on most products.
10 years ago when CDMA and TDMA came out there was a move to go to lower power. Most devices were putting out .6 watt maximum including car kits as set up by the factory. Now let me stress that from the manufactures ONLY analog was running 3 watts and since analog is for the most part gone its a non player.
I will also have to to look this up to be sure but I think the bands are also part of the output wattage. 800 MHz is licensed to 3 watts. I think thing the PCS 1900 MHz are licensed to 1.2 watts max but I think most are only .6 watt.
I thinks thats how this product is saying its 3watts is the band is licensed to 3watts even though on TDMA and GSM they run mostly .6 watt.
Low power cant be good you say???!!??......Cellular, GSM,TDMA CDMA all need channel reuse to be able to handle the user load. They depend on low transmit distances in dense user areas. A tower can only handle so many calls. So in dense use areas the towers are close together to give the system capacity because of the limited bandwidth available. Basically the towers 2-3 away will have the same channels as the one close to you. So they don't want you to transmit that far or they will have a "co-channel interference" (where two customers end up on the same channel).
Now phones have 7 power levels that the system will decide how much power is needed and adjust the cell phones power output to that level. Closer to the tower the less power is needed.
Now that you understand the basics here is what happens with that sort of "booster". That is a "liner amp'. Basically it is set to take a .6 watt signal and bumps it to 3 watts. It also bumps any garbage the transmitter is putting out or any garbage its own transmitter is putting out. Most are also wide spectrum so that the will work on both 800 (originally cellular frequency) and 1900 (PCS frequency) so they are dumping garbage on surrounding bands.
In a nut shell its a "dirty" transmitter.
Now remember the part about the system determining the out put power needed? Well here is what happens with one of these set ups when you get close to a tower. System cant turn it low enough so it gets pissed and dumps the call because its overdriving the band. Yee haaa dropped call. The channel reuse is also another reason why you shouldn't use it in a aircraft. You have the potential to hit multiple towers running the same channels since there is no ground clutter to limit signal.
Now notice at no time did I say it boosted the receive signal. If it does boost it it boosts it dirty.
If you read the fine print it clearly states that on 1900 it does not boost the power at all. It clearly says "Antenna gain only in PCS 1900 MHz Band". Knowing that it means the booster it will do nothing for Sprint, Nextell, and a bunch off smaller companies and half of the Cingular service areas. The antenna helps a lot but that booster will be passive and not producing any additional output.
Save your money and find a remote antenna that fits your phone. The antenna in most instances is going to be the biggest gain and best bang for the buck. The problem is most phones do not have a hard connection anymore so you are going to have to use a inductive coupled antenna and they have a good amount of loss.
One of these:
And one of these:
Is going to be the best bang for the buck.
Wilson is a reputable name in Antenna's. They are easily found in truck stops is why I pointed them out. They know the trucking industry s their bread and butter and they side lined into phone stuff that sells well at truck stop radio shops. Andrew, Antenna specialist are other good company's that make Cell and PCS products.
Few I have not cared for is Larsen and Maxrad.
Mixed about Mobile mark. Have used them some with ok results but it was limited to their glass mount. Interesting design....ok performance but cheap coax and had a few fall apart after time in the sun. Andrew and Antenna specialist I used heavily and always a strong performer.
A roof mount with a good ground plain is the best. Ground plane is a flat horizontal metal surface that the antenna uses to compress the signal against. If possible have it electrically common with the shield on the coax wire.
A glass mount, especially on our aluminum beauties, is the worst The glass mount is bad because it already has loss going through the window but the body is also going to make it directional so if the nearest tower is on the other side of the coach you might as well have no outside antenna because the aluminum body will block the signal.
Personally a magnetic mount (just as effective as a roof mount as Long as it has good ground plane) and a little tape to hold it down is great. Then when you are in the car you can throw it up on the roof as well.