From my Optimus S, I am unable to dial T-Mobile contacts most of the time. When I dial, there is silence, then an odd echo where I can hear my own voice. This only happens when contacting people who are on t-mobile. If I reboot the phone I can dial them once and connect, but then it's right back not being able to call. Texting works to/from t-mobile. I can dial any other numbers fine (Sprint, Verizon, AT&T, landlines, etc.)
Anyone heard of this?