my desk phone will start buzzing and I look at my phone and it has 5 bars of Edge. Know that the desk phone only buzzes when the phone is in Edge mode so I am able to tell EXACTLY when the change happens. That's my biggest annoyance with the phone dropping Edge...my desk phone becomes very annoying and I have to move my iPhone to the other side of my desk.
Sounds like interference. You need a landline desk phone or a different desk
phone. The two devices are obviously interfering with each other. If I get my iPhone too close to my portable home phone, they both get real "staticky." You need to revert back to a basic wired phone at your desk. Or trade your iPhone in for one of those cheap plastic go-phones. Haha!

Buildings do decrease signal strength a lot. I live outside of the city, but whenever I'm doing business in cities, I find that walking around the corner of a building can make a significant difference in cell reception. (Chicago, Los Angeles, Boston, New York, Dallas are the cities I have been in with my 3G iPhone so far) Just walking from one street, around a corner onto a different street and different side of a large office building can take my phone from 5 bars to 1 bar, or vise versa.
Your best solution is to move out of the city and live on the beach. Come down here to Orange County, CA. We have excellent 3G coverage, the beach, hot hot hot chicks in bikinis, excellent weather all year around, and a booming economy. And right now, you can get a really good deal on real estate.
Or, you can move to Galveston, Texas and there will LITERALLY be no buildings to block your signal ... if you can find a cell tower.

You can probably find a REALLY good deal on real estate there too. I heard used cars are only $500.
If you want more info on what you see below, go to
www.homeseekers.com and type in zip code 92660.