I am having a strange issue where phones are unable to dial internal extensions it will work but most of the time it will not, it will get a fast busy signal after dialing the extension then display on the phone unknown number then the buttons appear to be locked up for 4 seconds then the buttons start to work again. If I reboot the phone system it is fine for about a week. I have a UC560 that trunks to a 2960 switch with vlan 1,100. All access ports have auto qos voip cisco-phone with spanning-tree portfast disabled. On the trunk I have auto qos voip trust. Whats weird is this has been working for years and out of the blue this is happening. The trunk interface has no errors. If I need to provide more details please let me know.
Phone System: UC560
Phones havng the issue: SPA525G2
Conference Phones: Do not appear to be having the issue, tried dialing extensions over and over and always works.
This is still an ongoing issue, even have a ticket opened with Cisco we are doing debugs and show commands. Were even doing a span port to do a quick wireshark capture. When in this state I have learned that telnet and SSH are unable to connect via vlan1 or vlan100 to the UC560 but ICMP still works and CCA still connects. The conference phones still show that they are unaffected.
7960 had the same issue as the 525G2 but worse, when dialing an internal extension then hanging up you pretty much lost connectivity to the UC560 via SCCP because the buttons become unresponsive and no dial tone. eventually the 7960 will reboot automatically. giving a message about lost connectivity to call manger.
Working with Cisco Level 2 support, we upgraded the IOS and will monitor and hopefully make it through the week with no disruptions. Current uptime after upgrade is 3 days and 15 hours.
Older IOS: 15.1(2) T4 with CME 8.1
Upgraded IOS: 15.1(4)M7 with CME 8.6
Because of other issues arising with the phone system, we noticed the FXO and FXS ports were all lit up amber with nothing plugged into them except for the two fax lines had no led lit up. The fax lines were not working as well. Cisco decided to send a replacement unit. FXO are not even used on this deployment, we use a PRI.