[cisco-voip] Back to back E&M trunk config example

[Jeffrey Girard]

Rich –
                Thanks for the response.

                Actually, 4 wires are in use

                1,2, 4,5

                1 -> 4
                2 -> 5
                4 -> 1
                5 -> 2

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Dr. Jeffrey T. Girard (Jeff), PhD
Colonel, United States Army (Retired)
Senior Network Engineer / VoIP Engineer - WireMeHappy.com
(607) 835-0406 (home office)
(845) 764-1661 (mobile)
(607) 835-0458 (fax)

From: Rich Davies [mailto:rich.davies at gmail.com]
Sent: Friday, November 21, 2014 10:07 PM
To: Jeffrey Girard
Subject: Re: [cisco-voip] Back to back E&M trunk config example

This may be irrelevant but your configuration references using "operation 4-wire" yet your E&M modified cable seems to only have 2 wires in use?

On Fri, Nov 21, 2014 at 3:02 PM, Jeffrey Girard <jeffrey.girard at girardinc.com<mailto:jeffrey.girard at girardinc.com>> wrote:
Im trying to mock up a lab version of a customer’s network.  They are using E&M cards to connect to some old computer based fire control systems that have embedded modems.

Of course, I don’t have access to any of these fire control computers to use in the lab.

Therefore, my thought was to simply use a Cisco 2901 as a “surrogate” fire control system, insert an E&M card into it, and configure it back-to-back with the actual Cisco router (with its own E&M card) used as the voice gateway in their network.

I have taken a look at the configuration used at the customer location for the E&M card that connects to the modem.

Relevant information follows:

voice-port 0/1/0
auto-cut-through
operation 4-wire
type 2
timeouts call-disconnect 3
connection trunk 1004
!

This is what I currently have:

Cisco 2921 replicating the customer router.  Config is as follows:
auto-cut-through
operation 4-wire
type 2

I have a Cisco 2901 attempting to replicate the modem in the customer fire control computer with the built in modem.  Config is as follows:
auto-cut-through
operation 4-wire
type 2

I have connected the E&M voice ports together using a  modified UTP cable.
Pin 1 to Pin 4
Pin2 to Pin 5

Of course, I have done a shut / no shut on both ends to activate the changes on the voice port

So, this is what I end up with

On the E&M cards, the “In Use” light illuminates soon after I plug in my cable.

Executing a show voice port summary command (on both ends) shows
Admin status – up
Operational status – up
In Status – seized
Out Status – seized

Note that I have not configured any dial peers (yet) nor do I have the voice ports in the “connection trunk” mode.

I have spent the last hour searching Google, with no results.

So, anyone with a working config that they would care to share for a back to back E&M connection – or can shed some light on why my voice ports are seized?

I tried 2 other cables pinned out the same way with no changes.

I attempted to add dial peers, and all calls failed (as expected).  Ccapi inout debugs showed the failure reason to be “busy”.  I expect this as my voice port summary is showing that the line is already seized.

I have rebooted the router, unplugged and replugged the cable, shut down the port several times.

I have also tried Type 5 with same results.

Any help appreciated.

Jeff
--------------------------------------------------------------------------------------
Dr. Jeffrey T. Girard (Jeff), PhD
Colonel, United States Army (Retired)
Senior Network Engineer / VoIP Engineer - WireMeHappy.com
(607) 835-0406<tel:%28607%29%20835-0406> (home office)
(845) 764-1661<tel:%28845%29%20764-1661> (mobile)
(607) 835-0458<tel:%28607%29%20835-0458> (fax)

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