NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

[Wylie13]

We're running NEC SV9100 (WebPro 10.00.00) and have stable NEC DT900 phones on Firmware Version (02.04.00.00) that have been online for over a year without interruption. Recently, we've provisioned more DT900 phones on Firmware Version (03.00.02.00), but occasionally they present a screen with a message of "Log Off" and allow you to press soft key for "Exit" and the phone resets, goes through LLDP Receiving and DHCP Connecting then allows for normal use. Aside from the obvious firmware versions being different, I do not know what is causing the newly provisioned phones to experience this issue and am not sure how to rollback the firmware or if some other variable could be implemented? Any assistance would be very appreciated.

 

[Wylie13]

DoubleDizzle,

After discussing it with our CrowdStrike team, nobody believes that it's installed on the phones. It's been suggested that I implement WireShark on one of the switches that has a phone connected and go from there. Any thoughts on that or anything that might point us back to CrowdStrike?

Thank you.

 

[DoubleDizzle]

Hello Wylie13,

A port mirroring switch could be installed between a troublesome phone and LAN cable to it.

Then connect a laptop to the mirroring port running a countinuous ring buffer capture file.

See attached docs...

Watch and observe when the phone went offline and analyze the captures from that timeframe.

 

[DoubleDizzle]

and this