Hell, we still convert people with 1980s Meridian phone systems. Those are not candidates to do anything but move to an IP handset.

-----
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com

Midwest-IX
http://www.midwest-ix.com

From: "Robert DeVita" <radevita@mejeticks.com>
To: "Al Whaley" <awnanog@sunnyside.com>, nanog@nanog.org
Sent: Thursday, September 12, 2024 10:44:08 AM
Subject: Re: Third Party VoIP Over Xfinity

Just push these end users to use softphones. There are very few use cases where a hard phone is necessary.

Robert DeVita

CEO and Founder

t: (469) 581-2160

m: (469) 441-8864

e: radevita@mejeticks.com

w: mejeticks.com

2323 N Akard Street

Dallas

75201

From: NANOG <nanog-bounces+radevita=mejeticks.com@nanog.org> on behalf of Al Whaley <awnanog@sunnyside.com>
Sent: Wednesday, September 11, 2024 6:50 PM
To: nanog@nanog.org <nanog@nanog.org>
Subject: Re: Third Party VoIP Over Xfinity

You don't often get email from awnanog@sunnyside.com. Learn why this is important

My recent experience with Comcast Business is that it does not permit fixed-IPs with either bridged mode or customer modems.

Also they have a 'feature' called SecurityEdge which is now on by default (didn't used to be). It blocks all sorts of things but currently it is possible to go to the account website and turn it back off. It's pretty evil for anyone that wants to, e.g., run a DNS server (evil = not possible due to a number of things including caching things it shouldn't etc.). I don't know about SIP as I have not attempted to run SIP over that particular connection, but I wonder if it might interfere.

On 9/11/2024 16:06, Tim Burke wrote:

They do not do CGNAT, as far as I know. (Fixed wired broadband should never be behind CGNAT, but that’s a topic for another thread :-) )

Should only apply if you are using Comcast’s CPE for NAT. I had Comcast service some time ago, using their rental CPE in bridged mode, and had no issues with third party SIP. 

Sent from my iPhone

On Sep 11, 2024, at 17:44, Brandon Ambrose <bpambrose97@gmail.com> wrote:


Does this apply only to customers using their proprietary gateway or customers on a CGNAT service with them?

I have been a Comcast customer for years, with my own equipment, and have never had issues using Polycom SIP phones on RingCentral. 

This is getting a little concerning for me as we are planning to roll out SIP phones direct to users at home soon. 

Brandon Ambrose
Network Administrator

On Sep 11, 2024 at 6:15 PM -0400, Matt Hoppes <mattlists@rivervalleyinternet.net>, wrote:
I have not, but we've run these phones with SIP ALG devices before
without issue. I'll have them check.

On 9/10/24 9:17 PM, Tim Burke wrote:
Have you tried placing the CPE in “bridged" mode? It’s been a while since I’ve done anything with Comcast CPE, but I remember their CPE doing SIP ALG when acting as a router.

On Sep 10, 2024, at 2:17 PM, Matt Hoppes <mattlists@rivervalleyinternet.net> wrote:

I have an employee who has recently switched to Xfinity cable service. Ever since they switched their internet service their work phones will not stay registered for more than about 3 minutes.

These same phones have been used on many ISPs without issues. The same config has been used behind multiple levels of NAT without issues.

She was fine, until she switched to XFinity.

Of course, XFinity support is absolutely worthless.

Anyone from XFinity Tier 3 or such that might be able to offer assistance?

I suspect it's something stupid with either NAT overload in the modem or the modem not keeping the SIP channels open.

I've tried playing around with registration times without any success. And again, we've never had issues with these phones or this setup with any other ISP.