What kinds of third party SIP are you all having so much issue with?  I manage a lot of accounts using the big, hosted providers and plenty of the endpoints sit behind Xfinity/Comcast boxes without issue.

The dropping registrations just sound like timer and firewall configurations.  By rule, I try to always go bridged mode with Comcast provided boxes, but even when not I can't recall having an issue like this except via the normal things like ALG being enabled or some type of security inspections causing trouble.  And TLS is the way 100%

On Tue, Sep 10, 2024 at 12:19 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.