Razr V3i - call connection problem

Hi, a bit like everyone else on this forum, I need help!

I've had my V3i since March and it's been fine, but recently when answering calls - or dialing out - I can't hear anything on the line for a delay of up to 30 seconds. The call comes in and I answer as usual but it seems to take ages to kick in. If I put the call on to speaker I can hear the caller straight away.

Anybody else had this problem - or any ideas on what to do?