I recently updated my Iphone 3g to the latest version of software, 4.02,  and ever since,  I have been having problems receiving calls.  Most go straight through to voicemail.  However I am able to make calls.  I can still send and recieve txts however some txts take some time to come through.  The phone is not jail broken and I havent had any real issues on the XT network up until now. I was in Aus for a few days before updating the software if that is of any help to anyone.
I have checked the carrier settings and they havent changed from previous.  I am reluctant to restore to 4.01 as I will more than likely to lose all of my contacts etc.  Or is this the best thing to do?