Have a few questions.
Is the other doorphone also connected to the UCx? If so, I am sure you compared the ext programming?

When you say you pull the cable from the switch and power cycle, do you mean it is connected to a POE switch and when disconnected and reconnected it power cycles the doorphone?

Are their other SIP endpoints on this UCx?

A few things you can try.

If connected to a POE switch try another port.
If both doorphones are connected to the same UCx, swap the door phones. See if the trouble follows the doorphone or stays at the jack where the trouble currently is.

I suspect you have an issue on the LAN. I have never seen the issue you are describing and the problem was a result of the UCx.

Let us know more.

www.ucxdirect.com

Thanks for the helpful tips, getsomesun. I was finally around when it went offline this evening, and after futzing with it a bit, it's not even responding to ping requests. I think we might have a problem with the way it's connected into the switch.

We were having major issues with our POE switch getting power surges from lightening strikes. A strong storm would would blow most of the ports out on the switch, and necessitate replacement. I decided to isolate our outside POE devices a bit and run them through an ethernet lightening arrestor. I have the external devices on their own POE switch, and a cable from there to our main switch. Since I did this, we've had no issues at all.

I wonder if there's something wrong with that port on the lightening arrestor that's causing it to go out intermittently. We have the same setup in the other building, and there aren't any problems there. Will try and switch ports and see if that makes a difference. Appreciate the help!

If you cannot even ping the phone, the problem is caused either by the network or by the device itself.

You could get "funny" behavior like this if you have multiple DHCP servers on a single LAN. The SIP device (your doorphone) could get an IP address from one DHCP server, run fine until the other DHCP server leases the same IP address to another device - the IP address conflict is detected by the SIP device, which handles the situation by shutting down its network stack. After that, the SIP device does not communicate on the network (including no response to ping). Another possibility would be getting a valid IP address from one DHCP server and later after a lease expiry (typically one day) a bad IP address (not in the LAN address range) from the second DHCP server.

Anyway, what I wanted to suggest is to check if there is a rogue DHCP server on the LAN with the SIP doorphone that exhibits this problem...

UCxguy brings up a good point. You can also have another device connecting to the network that may have the same address statically assigned. to confirm this, get IP address of the doorphone, make sure it is pingable. then disconnect it from the network and try to ping again. If you get a response then you have to devices on the network with the same IP address.

What was the result of swapping the port?

Also, if you swap the doorphones this will quickly tell you if there is anything wrong with the port or the cable between.

Keep us posted.

www.ucxdirect.com

Well ... I did a bit more testing, and still can't find the culprit for sure. I think the doorphone swap is the next thing to try. We only have one DHCP server on campus ... there aren't any other devices that have DHCP services built into it that could cause consternation on the network. As soon as the UCx reports the doorphone offline, I ping the phone's IP address and get no response, so that's telling me that there's something going on with the doorphone itself. I had this problem back in January, and it was like it is now ... going out every other day. Then ... all of a sudden, it stayed online for the past few months without issues until this started up again. I did try to switch ports ... no help. I could try and plug it directly into our main switch again, but I risk the possibility of blowing it out in the case of a storm.

Maybe I'll do the swap and we'll see if the issue follows the phone. Thanks for all the help thus far.

-M

I thought I'd provide a brief follow-up. The folks at Fanvil have determined that it's something buggy with the doorphone. It's been online for almost three weeks now without going offline. If it cycles again, they'll have us remove it and they'll send us a replacement. This place is full of "unique challenges!"