Building a Personal VoIP System

Excellent article, and sections "NAT Problems" and "NAT Solutions" are a good starter on that topic.

Except even third-choice solution is not always feasible. Reserving fixed RTP/UDP port range is not possible with carrier-grade NAT, which is quite common with residential ISPs and nearly-universal with cell ISPs.

Fourth-choice would be to reserve port range on a personal server (which would run B2BUA, asterisk in OP's case; or an RTP proxy), and force calls, including media, from/to SIP handsets to go via that.

This was sort of a thing in the mid-2000s, and I’m actually surprised to see it again. At the time I expected home routers to become SIP endpoints (and that came to pass with fiber), but they all expose FXO interfaces (jacks) rather than act as proxies for soft phones, so there’s a missed opportunity there. But the truth of the matter is that just shipping a DECT phone in a bundle is much easier for the carrier to troubleshoot.

Cool to read someone indulge in this. For others interested with no prior context, also consider FreeSWITCH.

Personal experience:

I spent about 15 months working for a local telecom company, supporting their asterisk servers and developing interactive voice response applications. I was given the opportunity to build their residential voip service (in 2010?) from scratch and despite asterisk being so dominant I prototyped and eventually completed the project using freeSWITCH. I found it to be so much more developer friendly to configure and extend. Being able to build dial plans and implement logic with JavaScript or Lua rather than asterisk's config files was worth it. I suspect this system is still running.

my wife had a requirement: be able to have an intercom for the house and shed. We used to have a baby monitor, but that was one way, for one room. Now we need many more rooms to talk to each other.

I looked at some intercoms on amazon/ebay, they are all RF and a bit shit. I saw some wifi ones, but nothing cheap enough to take a punt on. I did think about trying to make something with an ESP32, but that would be too hard for me in the time.

So I bought 6 cisco 7962 sip phones for £35 in total, and installed freepbx.

It took a bit of effort to bring the tftp server online, and make sure all the dhcp info was being passed on correctly. Once that was complete, freepbx makes most things pretty simple.

Now, I have ethernet is most rooms, and a switch that can do PoE, so this solution is for a niche of a niche

Does anyone have SIP setup on their domain? Are there many spam calls these days?