Can anyone help me in solving Time Slipping on D500? The PBX is having an issue with clock slipping every 2-3 weeks. Lately, it seems be happening every week. 2 PBXs are linked in a master-slave setting. The master PBX is set for network clock. When the master sees the time slipping, it uses its own clock acting like a master clock. We cannot receive/send fax. Is this T1 issue? Or, PBX timing issue? I'm wondering whether we should change the T1 carrier.