Since I switched from AT&T iPhone 3G to Verizon iPhone 4 I have complaint about data signal strenght, but i have learned to deal with it since it works 80% of the time.
Could someone though explain to me why when I was in a moving vehicle with two iphone 4's in the car one had 3G and mine kept switching to 'o' data speeds? Can one phone steal data from another? There was also a HTC Trophy in the car but not being used at the time.
There is already a thread about this problem that iPhone users are experiencing. I have the same issue and I'm in downtown Dallas, TX. From what I've gathered after having both AT&T and Verizon, Verizon's 3G signal is pretty weak which is why it switches to "o".
Are you still experiencing this opportunity? From the sound of it it may be a specific device issue if another VZW device had service in the same area. Please navigate to Settings>General>Network and turn cellular data &data roaming off and back on (will not be charged roaming fees unless you go outside the country) and make sure wifi, personal hotspot is off. Power cycle after changes and retest. If that does not assist you would want to restore the device thru itunes and reactivate. Keep in mind this will erase everything from the device so please back up if desired. Please let me know if this assist and if not we can move forward. Thank you.
Alternatively, you can just Reset Network Settings or try updating Roaming (*228 Option 2). That might be easier than wiping your entire phone clean.