Phone Hangs on "Contacting Server" - COMCAST?

[Kaeri]

Good morning!

We have the Mitel 5000 brain, with multiple 5340 IP phones off-site.

Most are in home offices around the city here – i.e. same ISP (TimeWarner).

One is in a home office hundreds of miles away in Atlanta, Georgia (Comcast).  In late February the Comcast user returned to Georgia from a business trip up here (Rochester, NY) and called because neither her phone nor her VPN software were working anymore.  Both had worked previously, and the VPN software continued to work everywhere except through her home connection.


We were on the cusp of installing a new firewall in her home office, so we ignored the issues for a week and installed the firewall. Firewall now works perfectly, however phone continues to hang on "contacting server".

Had the phone, cords and power brick all shipped back up here.  Configured a new phone, power brick, lan cords, and took them off site and tested – phone works perfectly. Packed it up, shipped it to Atlanta, she connected to her network - no joy, same hang on "Contacting Server".

The Comcast modem is in virtual bridge mode, so they say it is doing absolutely nothing with the traffic. The firewall has a trusted port configured for phone traffic – problem occurs on that port. Also has a port configured wide open (DMZ) in case we need to test anything outside of firewall rules – problem occurs on that port as well.

I suspect the issue is the Comcast connection, particularly since the problem started prior to installing the new firewall, but I'm not sure how to check or test or even what language to use when calling their techs to troubleshoot...

Logs from the firewall:

networkd [eth2 (Trusted Phone)] Interface link status changed to down id="3100-002C"
networkd [eth2 (Trusted Phone)] Interface link status changed to up id="3100-002C"
networkd [eth2 (Trusted Phone)] Interface link status changed to down id="3100-002C"
networkd [eth2 (Trusted Phone)] Interface link status changed to up id="3100-002C"
dhcpd DHCPDISCOVER from 08:00:0f:5c:bd:96 via eth2 id="1600-0066"
dhcpd DHCPOFFER on 192.168.4.2 to 08:00:0f:5c:bd:96 via eth2 id="1600-0065"
dhcpd DHCPREQUEST for 192.168.4.2 (192.168.4.1) from 08:00:0f:5c:bd:96 via eth2 id="1600-0066"

10 minutes or so later, this sequence will repeat.

2016-04-06 09:46:17 dhcpd DHCPACK on 192.168.4.2 to 08:00:0f:5c:bd:96 via eth2 id="1600-0065"

[Tech Electronics]

Kaeri,

Well, the problem sounds as though it is at the users home connection. Is their VPN connection back up and working or no?

Thanks,

TE

[Kaeri]

Hello TE!

We installed a firewall at the location that eliminated the VPN software client, so I don't know - but I suspect you're right.

Can you think of anything in a bridged modem that would interfere? 

Originally, Comcast still had DHCP turned on in the modem's "virtual" bridge mode - and I was excited because it seemed obvious that was the problem.  Unfortunately, the problem persisted even after we turned the DHCP on the modem off and rebooted the whole system.

[Tech Electronics]

Kaeri,

The phone has to have a few things in order for it to be able to get to the phone system.

1. It has to have an IP Address on the network it is sitting on.
2. It has to have a gateway to get out to the network the phone system is sitting on.
3. It has to know how to get to the phone system.

So when it was tested at the home office how was it tested? Did someone take it home and use Teleworker mode on it to get it working? Did they have a VPN connection into the network with the phone system? Is the phone setup for NAT or Native?

Thanks,

TE

[Kaeri]

Hi TE!

All offsite phones are set the same way, four simple steps!

1) In the Mitel system, they're switched from "Native" to "NAT"
2) The phone itself is reset, then
3) The ICP Address is set to our external IP, and
4) The TFTP SVR IP Address is set to the same external IP

When the phones are taken offsite they get a power brick.  Power brick gets plugged into the electrical port, one LAN cable goes to the phone, the other LAN goes to any open port on their home router.  The phone boots up, reaches out to our external IP and is then provisioned an IP, etc. - no on-site configuration required.  We have a half a dozen phones set up this way - including the Atlanta phone.

Periodically they cycle through a boot on their own, or fall behind with the date/time, but they all otherwise work fine.

Except this one!  This one went through a boot cycle in Feb and hasn't connected since.

[Tech Electronics]

Kaeri,

Well it sounds like it should be setup properly and that the issue has to be at the user's home. I would have them take a picture of their setup from the switch to the power brick to the phone and make sure they have it physically setup correctly; most likely they do.

After that you will need to get access to their local router and see if you can't find anything that would cause the problem. If that doesn't show anything obvious then you will need to do a port mirror on the phone, instructions are on this site, and the phone system. Then setup wireshark and see what is being sent out from the phone and see what is being received at the phone system. My guess is there is some sort of transformation from their site to the phone system since everyone else is working fine.

Thanks,

TE

[Kaeri]

TE - Have done the first & second part, but that port mirror sounds like just the thing,  I'll search the site for instructions.

Thanks so much for pointing me in the right direction, I'll let you know what I figure out!