I'm with Telstra and with a @bigpond.com email address and have had no problems which leads me to think Telstra hasn't set up your IP address correctly.
I have an Iphone and a laptop and have no problems apart from poor signals. God help me when they turn off the 3G because I will loose all services then.
Best of luck. Try ringing complaints about 2am in the morning as it manned in Aust then not Manilla.
Oh, and be very polite as that gets a better result.