Reverse from usual problem, Calls drop 3G!!!

Question

Hi all.
I have read reports of 3G connection causing calls to be dropped. I have the exact opposite problem.
Every time I answer or make a phone call, my phone drops from 3G down to a 2G connection so I cannot use internet while talking on the phone. The 3G connection is also extremely flakey. This is on firmware 2.1.
My first iPhone 3G did NOT have this problem, but it had a really sticky home button and sleep button, so I got it replaced. The new one worked fine for a few days, now is very flakey with 3G connection.
I must say, I'm very unimpressed with this phone. I don't want to have to replace the **** thing every 2 weeks for new defects each time. Apple's quality control seems to have been flushed down the toilet lately, they haven't been able to manage a good product launch in years.
Has anyone had this problem, and is there any way to fix it without restoring or replacing?
And please Apple, could you just make the 3G iPhone work like the original. I've already recommended several people buy competing phones because I can't in good faith recommend this product to anyone that I don't have a grudge against!

Answer 1

When you see a beachball cursor or the slowness is especially bad, note the exact time: hour, minute, second.  
These instructions must be carried out as an administrator. If you have only one user account, you are the administrator.
Launch the Console application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad and start typing the name.
The title of the Console window should be All Messages. If it isn't, select
          SYSTEM LOG QUERIES ▹ All Messages
from the log list on the left. If you don't see that list, select
          View ▹ Show Log List
from the menu bar at the top of the screen.
Each message in the log begins with the date and time when it was entered. Scroll back to the time you noted above.
Select the messages entered from then until the end of the episode, or until they start to repeat, whichever comes first.
Copy the messages to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.
The log contains a vast amount of information, almost all of it useless for solving any particular problem. When posting a log extract, be selective. A few dozen lines are almost always more than enough.
Please don't indiscriminately dump thousands of lines from the log into this discussion.
Please don't post screenshots of log messages—post the text.
Some private information, such as your name, may appear in the log. Anonymize before posting.