This is just my experience, YMMV as they say…

In April of 2022 my VOIP home phone stopped receiving incoming calls. I could still dial out, but nobody could call the house. I received warning emails from Skyetel every 3 hours that my SIP endpoint was unreachable by their servers.

Since nothing had changed on my end, I suspected that something changed with my provider: Comcast/xfinity. Similar to my experience with British Airways, I found that xfinity has now automated everything.

I understand that automation helps if someone just needs to reboot their router, or forgot their wifi password. But for those who need genuine help getting shit done, it presents a huge barrier. It took me 9 calls and 3 trips to the xfinity store to get this resolved…

Approach 1 (trying to fix the problem directly)

I phoned tech support to explain that port 5060 (for SIP service) was being blocked on my connection.

The first guy I talked to said they won’t open up that port unless I subscribe to xfinity’s VOIP service. Honestly, I didn’t want to talk to this guy anymore. He was obviously from India. No offense, but he sounded more like a scammer than a helper. I wanted to talk to someone who actually works for xfinity in the US, that actually knows how their network is set up. Before I hung up I got the phone number for Advanced Technical Support. It’s 888-780-8571. You’re welcome.

I called that number and magically wound up speaking with an actual technical rep based in these United States. BTW, this won’t happen every time – I’ve yet to figure out what automation magic I did to skip past the overseas nonsense.

When I mentioned my issue he referenced this page https://www.xfinity.com/support/articles/list-of-blocked-ports which I had also been looking at, noting that port 5060 isn’t in the list. He said I might need to do some configuration in my modem’s settings to forward that port.

But the Netgear CM1000 isn’t a combo modem/router. It doesn’t have a firewall or port forwards or anything. It just passes all connections on to my OpenWRT router which has firewall/forwarding/wifi/etc.

So the tech guy suggested I try an xfinity-supplied cable modem (at a rental fee of $15/mo) to see if that solves the problem. I wasn’t thrilled with the extra cost, but he said it’s pro-rated and might be worth seeing if it fixes the problem.

Approach 2 (playing the game)

So I went into my nearest xfinity store, went home with a new cable modem, and set it up. Then, to my dismay, when I went into the port forwarding settings on the modem, I consistently got this error:

I called technical support back and they said:

You need to go back to the xfinity store and get a different modem that is supported by the xfinity app. I’ve made a note on your account so they’ll give you the correct one this time.

WTF. OK, so I went back and returned my modem for another one. The new one worked with the app. I did have to do some weird things like disable IPv6 on my router so that it would show up in the xfinity app as an available device and port-forward destination because xfinity only supports port forwards via IPv4.

What’s really going on?

After configuring the router and updating my IP at Skyetel, it seemed to work 💪 Our home phone now rings after dialing. I called xfinity tech support again to re-activate my Netgear CM1000 to see if it will continue to work. Hey – it worked… But why?

My hunch is that by selecting a port forward in the app, something else is getting configured in their network to allow incoming connections – something upstream from your rental router. We’ll see how long the setting lasts before I have to go (temporarily) rent one again 🤞 Also – I was able to reactivate IPv6 in my router without issue.

The next day, the phone rang and it was music to my ears! ☎️ It was my daughter’s friend and they made plans to get together. Then the day after that, I received my first spam call 😱