I've had an LG ipLDK20 from new (now 18 months old) and have had the same problem 3 times now. It appears to intermittently 'fail' and cuts the lines off. If someone tries to call they get 'this number is not known'. We run with 2 ISDN2e lines giving 4 channels. There are 2 BT ISDN boxes on the wall with a green light. When the unit 'fails' the lines flash. Sometimes it just corrects itself, other times we have to turn off at the mains to re-boot, which works for a time. Has anybody any ideas, and also is there someone out there who can offer a fix. We're based in Worksop, nr Sheffield.