We have a problem at one of our clients, they are reporting that when they are being put on hold by someone from another location that after 10-15 minutes the call just drop off. It has happen to several people calling different places. They have a Merlin Magix 4.0 with PRI. The provider said that the problem is not them. I'm having a hard time believing that it the phone system. They are not reporting any other problems. Anyone have any ideas on what could be cause the problem?