Telephony & Fax with OpenWrt. Is there a preferred way?

I wonder which is the preferred way for telephony & fax with OpenWrt.
In the past i have used AVM devices provided from my DSL provider. The devices have had always an internal PBX.
In these old AVM day's I have had only one common network, and one WLAN. With OpenWrt I'm using different VLAN's to seperate VOIP, IOT, parents (>80 years of age), children, ...

Now, in my new AVM-less OpenWrt world I had to decide how to do telephony & fax.

For most communication we are using smartphones, but there are 6 wired (hardware) sip phones left in my family.
And we like to use these phones in future too. I.e. for homeoffice work, parents, ...
At the moment these 6 phones share 4 sipgate accounts. They are directly connected to sipgate. But using this method drills some holes into the firewall. And phone firmware updates are rare.
Normaly there is no need to dial numbers with the house. To call my parents I just dial the external number...
Configuration of phones was quite easy. Just create (mostly copy&paste) config files and store them on a local https server.

So I'm asking if it would be a better, more secure way to use a PBX (Freeswitch ?).
Using this method only my router will connect to sipgate.

The other site is fax. There was a buildin fax receiver in the AVM Box, and I had redirected all received faxes to mail.
Sending fax was easy too. Just connect my Lexmark MC3326adwe multifunction printer to the AVM Box with a RJ11 cable. This way my parents can send a fax without asking me for support.
Of course I can add a VOIP to analog fax gateway in my setup. But this is solution will eat up much standby energy while it is used only 5-10 minutes a month. Not really a green solution.
So I'm asking if there is a easy way to get it all. Easy configuration, easy handling, low energy consumption.
Maybe Freeswitch on my NanoPi running OpenWrt is a good solution for receiving fax. But what about sending a fax?

And I haven't found much about using Freeswitch on OpenWrt. So it could end up in a long way to make it run reliable...


Did you find this?

Yes, I found that.
But thats only usable if you know what you want. It did not help to make a decision nor it provides information about pros and cons of solutions.
I have read somewhere that "gemeinschaft" has changed from asterisk base to freeswitch because of security.
Asterisk is a really heavy PBX, with tons of functions I will never use.
The Freeswitch entry points to No easy starting point.
And there are no answers to my questions ....
And siproxd just allows "SIP clients to work behind a masquerading firewall or NAT router".
But this is already working, without siproxd. So why should I use it?

It would also be possible to configure your old AVM device for IPoE mode, as a client device (not using it as modem, router, AP, etc.) only acting as SIP pbx/ ATA, DECT base station and fax gateway (locked into its own, separate, VLAN if your like) behind your OpenWrt router. That would be the simple solution…

…but full asterisk/ freeswitch, etc are of course at your disposal as well (supporting all but DECT), enterprise ready - but not exactly a fun exercise to configure and set up.

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I can't tell you the preferred way for telephony & fax with OpenWrt, but I can tell you, how I managed the problem.

I have several IP-phones (Gigaset GoBox100), my SIP provider is easybell in Germany. The IP-phones are NOT directly connected to easybell.

Instead I installed the yate software on my OpenWrt router. My IP-phones register with yate as their SIP provider, on the other side yate registers with easybell as its SIP provider.

So yate acts as a SIP server towards the phones, but as a SIP client towards easybell. As server yate listens on the LAN side, as client it uses the WAN side. So yate needs no hole in your firewall.

As side effect you can make in-house calls without using your external SIP provider.

I'm not sending faxes with an analog fax device via VoIP. Sending faxes/data with an analog device (fax or modem) is highly unreliable, at least with the devices I have.

Instead I use a service of easybell: as customer you can upload a PDF file to fax. When you dedicate one of your phone numbers as fax number, easybell will send incoming faxes as PDF files via mail to you.

That's my way to handle fax and phone. If you have any further questions, don't hesitate to ask.

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using an old AVM Box could be an easy solution. But it is not a ecologically nor a economic one for my scenario.

Let's assume the box has a power consumption of 3W and a there is price of 30 cent per KWh.
3W * 24h * 30days * 0,3€/kWh = 65 cent/month

If I follow Barney's tip an use a fax account. I.e. at each fax page will cost 7ct, I can send at least 9 pages a month.
Much more then I need. Even if I assume the power consumtion of the Fritz!Box can be reduced to 1W, I can send 3 pages/month.

And of course the additional device will heat up my rooms a little bit too. So I have to invest more into my air-condition in summertime.
Ok, in winter times I can save lots of oil for heating :slight_smile:

So my decision is to make the first step and give fax via email a chance.