Re: Third Party VoIP Over Xfinity

[Tim Burke <tim () mid net>]

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.