"There are towers 7, 9, and 11 miles away." Your phone should be able to work with those. The problem is that all cell phones work based on what is called the "FM Capture effect". That is, the tower locks on to (captures) the xx strongest signals, and whenever a stronger signal comes in, it knocks off the weakest one. So if your local tower is able to handle 100 calls at the same time, and you are the weakest signal, along comes someone on the highway, 101st caller<G>, gets closer to the tower, stronger signal, and bam you are knocked off the air, your call gets dropped.
Doesn't matter how clear your call was--a stronger signal knocks you off once the tower reaches capacity.
Check out Antennaworld (as usual, dot com) they have been in the real world of marine/aviation/cell antenna business for a long time and have some good stuff, as do a couple of other places. With those distances I would go with a yagi, which has to be pole mounted. If Samsung is right about that being an MCX connector...they probably can make up the right cable for you, custom, if they don't have a pigtail for it.
If you don't want to be tied to an antenna near a window (long cables kill the signal, so you want a short antenna cable) the next step up is about $300-350, which is to get a "repeater". That's a cigar-box sized radio. It gets mounted outside and high, with an antenna like the yagi, and then it acts like your own personal local cell tower, so your cell phone has a clear strong signal within 100' or so of the box.
This is not the "picocell" or "femtocell" that the cellular companies are selling now, it doesn't connect to the internet or your phone line. It is a two-way booster that stays completely on the cellular system, and will work for an cell phone near it, as long as they are the same frequency. The cheaper ones do not have full power, the real ones probably won't be under $300.