A network issue doesn't seem to be supported by the evidence. Some people have this problem consistently on every call, others don't ever have the problem. But it could be a regional thing. For me, it happened on nearly every call - and every call over 5 minutes - for a week and a half. The second I popped a new SIM card in it stopped and hasn't happened since. But others are still having the problem. For a network issue to be corrected in my area at 7:30 PM on New Years Eve precisely when I got the new SIM card would be quite a coincidence. The theory of SIM cards being to blame fits all of the cases I've seen so far, including yours. As I said to jrbmed08, if it is indeed caused by bad SIM cards, then you would expect some users to get a bad SIM card the second time around, too. I freely admit that I simply haven't seen enough data to conclude that SIM cards are to blame, but for whatever reason swapping them out has eliminated the problem for multiple users. One possibility is that there is some other variable that is resolved by swapping a SIM card.