The problem is NOT related to signal strength. The connection switches randomly between 3G and Edge at ANY signal strength.
You can access Signal Strength at Settings/About Phone/Status
The following conditions were observed by moving to different locations (NOT chronological order) in and out of the house:
dBm / ASU / Network / Bars
-63 25 3G 4
-63 25 Edge 4
-77 18 3G 4
-77 18 Edge 4
-89 12 3G 3
-89 12 Edge 3
-101 6 3G 2
-101 6 Edge 2
-109 2 3G 1
-109 2 Edge 1
dBm and ASU are the two signal strength readings on the phone. Bars is the signal "bar" readout in the top indicator bar.
Even with the STRONGEST signal, the phone is unable to reliably connect to the 3G network. Furthermore, the phone clearly DEFAULTS TO BE ON EDGE under even ideal conditions. Had a friend over yesterday with their G1 on Tmobile and they had constant 3G while I had Edge 90% of the time. This was everywhere in the house. Over the last 2 days I find I get 3G about 10% of the time. I'm in clear sight of a T-mobile tower and am supposedly smack dab in the 3G coverage.
This appears to be a software problem- either a complete design failure on the part of T-Mobile/HTC or a designed "dumming down" of the phone to reduce network congestion.
THIS MUST BE FIXED, or my phone is going BACK within the 30 day (by law in CA) return period unless T-mobile fixes this COMPLETE DISASTER. HUNDREDS of posts here about this problem:
Spotty 3g? - Google Mobile Help
San Leandro, CA near 580 in an elevated location with clear shot to at least one T-mobile tower.
Follow-up regarding DOWNLOAD SPEEDS
Download test speeds under -63dBm (4 bars) conditions have been observed as follows:
Edge (4 bars / -63 dBm) from 24kbps to 180 kbps
3G (4 bars / -63 dBm) from 100kbps to 820 kbps
Not even CLOSE to the "lightning fast" speeds promised by HSDPA7.2 !!!!!!!!