I have a customer who has had a new IP500 installed and have a hunt group setup with 16 5420 handsets. On the spare keys they have been used for key and lamp with other ext on the system. Not all the time but between 10 and 15 time a day when a call is made into the group one person answers the call but the other 15 phones keep ringing. When they pick the phone up there is no call just dial tone when they put the phone down it will ring again. The olny way they can clear this is by unpluging the phone then putting it back in and it will stop the phone ringing. I have spoken to Avaya on this but they can not find anything in the traces i have sent then, or get the same fault in there lab.