Rj11 voip configuration

Hi all,

I have a Fritz!Box 7530 with Openwrt 21.02.1 with a FON1 port where I can insert rj11. I'm using it as third party router on a FTTH line, setting a VLAN ID for the line and all works fine Iget both ipv4 and ipv6 without any problem.

I need to configure the Voip to use my own cordless but in the GUI I am not able to find any tab for the phone configuration and using the shell I have no idea how to set the Voip parameters.

Could you help me and support for the configuration please?

Thank you very much

EDIT: I may be wrong about what I wrote below... the web page for the device states " * Telephone system for IP-based connections"

EDIT 2: I was totally wrong here... ignore all of this.

I don't have this device, so I'm commenting based on an educated guess here...
I would image than the FON1 port is actually a pass-through from the DSL upstream connection. In other words, it is essentially the equivalent of plugging your phone directly into the wall.

I don't believe that this device has the built-in hardware necessary to do VoIP to analog phone conversion.

Neither of these features are supported by OpenWrt on this hardware.

The FXS port (rj11) might be supportable, but AVM chose a different hardware design than other vendors using lantiq SOCs, so chan_lantiq as asterisk plugin doesn't work. Getting this working would require would require serious driver development, but it would be a task somewhere within reach; you'd still be left with the tedious task to configure, secure and harden asterisk though (which isn't for the faint of heart).

There is no DECT support available for linux whatsoever, neither basic stack support nor drivers, so this is a no-go.

If you want to use the phone features on this hardware, you will have to use the OEM firmware, not OpenWrt. These features don't need to reside on your router though, you can keep an OpenWrt router as gateway to the internet and use a (OEM supported) Fritz!Box in IPoE mode in your LAN (or a jailed-off VLAN) to cover your phone needs.

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Sadly, no - this UK style phone 'network' design is not used in Germany (traditionally with a central line splitter, splitting DSL and analogue/ ISDN services once, early; nowadays VoIP/ SIP only).

Exactly this, the Fritz!Box hardware contains:

  • SIP pbx
  • cat-iq 2.1 based DECT base station
  • some models still support for an analogue phone line coming in, get managed by the internal pbx software and go out (on the FXS port, up to 6 connected DECT handsets - or up to 10 internally registered SIP lines via ethernet/ WLAN)
  • some models also still have ISDN hardware (in- and out, including pbx support and all the features above).
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Thanks for correcting my understanding/guess. Fixing my post with strikethroughs so I don't mess anyone up later.

Based on this, I can use the Frizt with the OEM fimware plugged in the LAN of a OpenWrt router as gateway and the configure the Fritz for the Voip.

Just another question because I wasn't able to find these information on internet: is there any router where I can install OpenWrt and I can configure the Voip using the rj11 port?

Thank you very much

Yes, but only the FXS (rj11) port - and only using asterisk and its chan_lantiq plugin, getting this set up, secured and hardened is difficult, but possible (only consider this if you are already familiar with asterisk). Most lantiq based devices -except those from AVM- can do this, e.g. the O2 box 6431 (not recommended, 16/64, a very basic asterisk setup already weighs 13-14 MB), but there are also better devices. lantiq SOCs are relatively slow and low-end by today's standards (and vendors often used cheap/ bad wireless chipsets, often single-band, in their devices), so while possible, they don't make good routers (anymore).


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So based on this I need a router with lantiq chipset. I found this one Fritz 7360, is it a good choose?


No, as mentioned before, AVM has a special FXS implementation not supported by chan_lantiq.

Why not my suggestion above.

I'm very sorry Lynx, I lost your comment.

Could I plug the device you suggested in cascade to the openwrt and let it work?

Well it is just that I am a huge fan of the RT3200, which I think is the most exciting new basic consumer router for OpenWrt right now. Big user base and very active development. Includes recent WiFi AX technology.

Then for your analogue phone you could use the HT801, which is well reviewed. My feeling is get a premium OpenWrt capable router product with good specifications, and rely on a separate device to give you the RJ11 VOIP capability.

I imagine that if you try to get an OpenWrt capable device that includes the analogue phone capability it will either be impossible or a compromise in terms of specifications. So better to focus on getting something that is good for the core functionality (router) and then just use separate device to give the RJ11/VOIP capability. Rather than compromising the core functionality (router) just to get an all in one device.

Make sense?

I think with the HT801 you can just plug in an analogue phone and it gives a normal ethernet output that you could then just plug into your RT3200.

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