Cisco 7975 socket broken

[alfredobosca]

I have a new 7975 Cisco IP Phone that is disconnected continuously.

I followed the next steps:

- Change Network port

- Change Module Phone

- Change Phone

[Jonathan Unger]

Hi There,

Please navigate to the 7975 web page (go to the IP address of the phone in your web browser) and look at the "Debug Display" page. On the "Debug Display" page it should give you the reason for the last restart and if UCM has closed the TCP connection. Let us know what you find on those phone web pages.

Based on what is found there it might be best to run a packet capture from the phone side and the CUCM side to see if there is a network device in the path resetting the connection.

- Jon

[alfredobosca]

When I access to Phone web page the logs indicates UCM-closed-TCP continuously.

Best regards,

[Jonathan Unger]

The message that UCM closed the TCP connection does not necessarily mean that CUCM is actually the device that is closing (could be a firewall).

A few questions for you:

a. Are there any firewalls in the path between the phone and CUCM? If there is a firewall in the path, can you check the logs to see if it is closing your connection?

b. Are there any other phones at this location, and if so are they experiencing a similar problem?

If you do not have access to FW logs, the easiest way to confirm is to take the following packet captures:

1. CUCM Side

There is a great document here on how to take the CUCM packet capture.

https://supportforums.cisco.com/document/44376/packet-capture-cucm-appliance-model

2. Phone side

To get the packet capture from the phone side, you can enable the SPAN to PC port setting on the CUCM device page and take a Wireshark from a PC plugged in behind the phone.

Once you have both packet captures if you see in the phone PCAP that a TCP reset was sent, but do not see that same TCP reset show up in the CUCM PCAP, you know there is another network device in the path messing with your connection.

Please let us know if this helps!