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NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
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.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

Remote or on site phones?

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
On-site.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

That feature is for hot desking and being able to move your extensions around. Question, do all your extensions work at once and are they unique? Have you gone over your licensing to make sure you have enough? I mean it could be firmware but I haven't heard nor seen that anywhere.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
To my knowledge, all of the extensions work and are unique by being assigned a four digit extension. How would I look at the licensing to ensure we were covered? Also, I'm not familiar with hot desking. As far as I know this issue doesn't happen to our existing DT800 phones or newly provisioned DT800 only the DT900s that are newly provisioned.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

Look up SV9100 hot desk.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
Currently 15-05-39 - CTI Override Mode: Disable
Does this need to be switched to Enable to prevent this?

Licensing seems adequate:



RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

Wow, version 4? Well, possibly you do have a software issue. I would compare the programming on an older phone to a new one. I normally just copy that stuff. You have plenty of licensing.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
Any ideas where specifically I would compare the programming?

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

I mean, I suppose the first question is who installed these new phones?

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
Someone else within my company. Is there a specific place I can look to ensure the settings match the stable phones?

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

Settings in 15-XX would be a start.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

Check the settings in 10-46. Refer to the features and specs manual for details.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
Settings in 15-05 are identical with the following exceptions:

Building A
Stable DT 900
IP: 192.168.x.x
Firmware Version: 02.04.00.00

Building B
Unstable DT 900
IP: 10.137.x.x
Firmware Version: 03.00.02.00

They are in two different buildings and were added to the phone system about a year apart. Additionally, we had one DT 900 added to the phone system in Building B and then relocated to Building A, which also experienced the issue and was one of the phones configured in the batch of fifty discussed below.


Another question came to mind. There were about fifty or so phones added to the phone system at Building B in groups of six at a time, utilizing the Plug and Play method after entering the ADMIN credentials and SIP addressing on the phones. Is it possible that there was a conflict with extension assignment or DHCP addressing which could cause this issue and may ultimately work it self out?

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

Are you running version 4 on that system? Feature 3 from any phone will give you this. I am fairly certain DT900 phones were not out on that version and it could be your issue. Also, are you using VPN or NAT?

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
Is this what you're inquiring about?



No, we're not using NAT or VPN.

Also, while in WebPro, it doesn't present an option for DT 900, only DT 700/800. I've previously had the thought that the DT 900 isn't supported well, but the fact that we've had some DT 900s that were deployed over a year ago without issues, I moved past that theory. However, it is certainly possible...

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

Have you tried moving the phone to the local site to see if that is an issue?

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

Hello Wylie13,

Just a thought......

I recently installed a few older DT700 IP phones to a SV9100.

The phones came up and worked fine for a period of time then would show a screen with a message of "Log Off" until you press soft key for "Exit" and the phones would reset and work properly.

This would happen about every two weeks, usually over a weekend.

The phones firmware was updated with no resolution to the problem.

A port mirroring switch was installed between a phone and the network and a laptop was connected running a countinuous ring buffer capture file.

When the event occured again, it was found in the network trace that a security appliance running "Cyberhawk" began a TCP SYN scan on the phone.

The trace also revealed the security appliance eventually duplicated the phone’s IP address and then began hammering it with 1-byte UDP traffic from its own IP address to knock it off-line.

Once the IP addresses of the new phones were white listed, the issue was resolved.

It definitely would be a good idea to set up a continuous capture so you can see exactly what is happening when your DT900s go offline.



RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
DoubleDizzle,

That is exactly what is happening to the newly provisioned DT900s that are on Firmware (03.00.02.00). Any ideas on how to investigate and possibly resolve this here? We're utilizing CrowdStrike.

Thank you.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

Hello Wylie13,

I think the simplest way to start is obtaining the current IP addresses of the DT900 IP phones that are experiencing the issue.

Then work with your CrowdStrike admins to white list the IP addresses and monitor to see if the issue has been resolved.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

(OP)
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.

RE: NEC DT900 VoIP Phone: Log Off Prompts Exit & Resets

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.

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