I just bought a new T-Mobile G2. I wanted to turn on Wifi calling but kept receiving "W006.15 isp or T-mobile Network Error" and asking me to register.
After doing some research I looked at my cable modem/router logs and config. There were fragmented packets originating from the phone and the incoming fragmented packets were blocked. I disabled the "Block fragmented packets" setting and the phone was able to connect for Wifi calling
| posted on Monday, December 6, 2010 11:05 AM