[cisco-voip] IP Phones + MGCP FXS + Shared Lines

Ryan Huff ryanhuff at outlook.com
Mon Dec 18 20:45:33 EST 2017


It is interesting that this is not specifically documented anywhere, as an unsupported feature. My suspicion is that because, it does work, some to most of the time.


The typical symptom I've seen from shared mgcp fxs is a, "ghost ring". Pretty sure it has to do with the notify event in the MGCP protocol and how CUCM responds to that in a "shared line" scenario. No Anthony, that isn't me being empirical .... that is from an OLD TAC case, if I can find it I'll print to PDF and sanitize the secret bits and send it to you.


Clearly, the most appropriate thing to do is a code adjustment in CUCM to prevent sharing MGCP FXS lines.


-Ryan

________________________________
From: cisco-voip <cisco-voip-bounces at puck.nether.net> on behalf of Anthony Holloway <avholloway+cisco-voip at gmail.com>
Sent: Monday, December 18, 2017 5:48 PM
To: Lelio Fulgenzi
Cc: Cisco VoIP Group
Subject: Re: [cisco-voip] IP Phones + MGCP FXS + Shared Lines

No unfortunately, just gotta play the cards dealt on this one.

Actually, I'm not interested in changing anything, I'm looking for documentation that supports what these two Cisco employee have publicly stated.  I personally will only cite sources from official documentation, and not from web forums, regardless of who posted it.  Because, at the end of the day, that employee can be wrong, and Cisco does not have to take responsibility for the infraction.  However, in documentation they do.  Either they fix the documentation, or they fix the technology.

On Sat, Dec 16, 2017 at 4:00 PM Lelio Fulgenzi <lelio at uoguelph.ca<mailto:lelio at uoguelph.ca>> wrote:

Looks like the thread points you to sccp controlled fxs ports. I'm sure you have your reasons for wanting MGCP. Curious what those are.

Could you get away with ATAs?

Sent from my iPhone

On Dec 16, 2017, at 1:50 AM, Anthony Holloway <avholloway+cisco-voip at gmail.com<mailto:avholloway+cisco-voip at gmail.com>> wrote:

Does anyone have current information on whether or not MGCP FXS ports can be on shared lines with Cisco IP Phones?

No anecdotal or empirical evidence please.  I'm looking for documented facts, preferably the kind that doesn't require re-reading it like 10 times to come up with your own interpretation.

Check out what the two Cisco Employees are saying in this thread from 2010 (Spoiler - It's not supported)

https://supportforums.cisco.com/t5/ip-telephony/shared-line-between-ip-phones-and-fxs-port-with-sccp-setup/td-p/1045431

Are you a Cisco employee who likes to stick your neck out for internet strangers, and also believe this to be unsupported?  Please contact me.  Or not.  I'm not crying.
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