Miken, some months ago i had an identical problem to yours, disconnecting when phone rang and crackle, i had many conversations with karoo but from their end all was well,they could even tell me when i had disconected but could not figure out why, this went on for a while untill i discovered my problem.I did do a post on here as to how my problem came about and i shall have a troll to see if i can find it,but untill i do, this may sound a very very stupid suggestion, but just check your phone is plugged into the splitter where the phone should be, don't assume as i did that the connections on phone are correct.,,,,i'll get back to you asap.

Update...Found it, you was actually involved in the discussion.....
http://karooforums.net/index.php/topic,528.0.html