We have a large IPT install with over 1000 handsets. A remote site with approx 75 IP Phones experience an intermittent problem where phones lose dial tone and existing calls are terminated.
The fault appears at the same time every day for approx 5 - 10 minutes.
The phones stay registered with Call manager, ping connectivity from Call Manager to IP Phones is okay. Sniffer traces show no abnormal traffic on the Voice Vlan during the outage.
100MB circuits between sites have low utilisation. Sniffer traces show QOS values are maintained end - end during normal operation.
PCs do not appear to experience an outage and are connected via the IP Phones. A mixture of 7912, 7940 & 7960s are effected.
Any suggestions would be appreciated.