I have a linksys wip-300 voip phone which has a problem. When I first switch it on it registers to my sip provider and it works fine, it makes and receives calls, but then if I put it down for say half an hour and then pick it up again it no longer makes or receives calls. If I try to dial any number the display shows an icon with a big red cross on it and the word 'Invalid' and the phone won't receive calls either, it's as if it's jammed. It's fubar and the only way to get it working is to reboot it. I'm not too impressed with this phone. Does anyone know what causes this and if it can be fixed? My first thought is a firmware upgrade but linksys have no support at all for this phone, none. The phone shows it's using software 'SRPC1_FW_1.00.06.bin Sat Mar 11 20:28:24 2006', bootcode version 1.00.01. Is there a firmware update anywhere for this phone? Thanks for any help.