hello we have a new install and customer says held calls are dropping sometimes. and once in a while more than one will drop at a time. its the summit 100 configured 408. so far calls not not on hold arent dropping. i called and was left on hold for 20 minutes and never got dropped so i dont think its a timer. they also told me that the third caller doesnt hear message on hold. they get silence. any ideas would be appreciated. dave