For some time after successfully making a voip call the call would randomly drop out. Both Big Pipe and 2 Talk said the problem was not from their connections but 2 Talk could see that it was happening from their records. After some months of putting up with the problem I disabled one of my 2 Talk lines. Problem solved. I guess after the call was made on one line, the other line thought as there was no activity it closed the connection shutting down both lines. This may help anyone having similar problems.