ONT for GPON fiber with phone RJ11 jack support?

I am in the process of completly eliminating the ISP router (HGU, it is quite large and it will just act as a modem in the future, son no need to have such a big gadget on the desk) and installing a new main router openWRT based (now I have one but it shares functions with the ISP router, being the openWRT the DHCP and DNS and the ISP an AP and local ethernet switch to one part of the home, besides the fiber gateway).

But the ISP router provides voIP to analog phone conversion through the internal RJ11.

So the easiest way to continue having phone calls is to use a ONT with a built in RJ11 and configure it to route voIP VLAN data to the internal conversion system.

In a future I would like to change that and use the router as a simple voIP phone centralite with vooIP devices connected to it (besides an analog phone to get phone even when some part of the net is no working).
But it does not seem an easy task, so I am looking for an easy way of having what I do already have, but without the ISP router.

I have read that there are some ONT with rj11 jack.

Would it be easy to use it?
Any model?
Any inconvenient of doing it that way, deriving VLAN voIP data to the internal phone jack in the ONT?

Would it be better to do that at the router level?
I mean sending all the traffic to the router, and connect the wan interface using PPoE and then deriving voIP lan traffic to an ethernet port?

What gadget would I need to use in that port to connect analog phones?
Would that let me in the future to create a voIP centralite in order to be able to answer the phone via voIP phones/smart phone app even when I am not at home, using internet?

At that point your ONT acts as a router.... so not really a viable option as ONTs mostly seem to not be user configurable.

When faced with a similar problem years ago, I decided to get a stand-alone VoIP base station* that I simply operate as one of the devices inside my home network, that way I an in no need of VoIP functionality in the router (which allowed my an easier transition from my ISP's all-in-one router modem to using an OpenWrt router).
I believe that some of AVM's Fritzbox routers can be operated as VoIP base station to be run behind an OpenWrt router, depending on the model these allow DECT wireless phones and some have sockets for analog telephones.

*) I git a gigaset C610IP bundle of a base station and a dect phone since I had no analog devices I wanted to keep in service, worked okay, but by now has been discontinued, I would probably try the fritzbox as base-station route nowadays, mostly out of curiosity.

I have no previous experience with installing a voIP server (DECT system?).

My experience with voIP has been with online services with virtual lines hired from a voIP provider (netelip) and installing them in devices connected to internet and smart phone apps, configuring an answer machine and things like that.

So I am a bit confused about the path to follow.

I suppose that letting the work to the router instead of the ONT or a lan connected device would be more flexible and the best path to follow.

But using openWRT requires installing asterisk in it and configuring it (with no web interface?) and it does not seem a very friendly system.
Even being able to configure it on openWRT I still have the problem of connecting the analog phones at home (you know, ethernet connection not being at the right point for phones and reusing the existing phones too).

So if it is possible to connect some gadget to a LAN port with an analog output too, and configure it and being able to configure it as a voIp centralite in order to connect to it from voIP devices it would be great.

What I would like to be able to get is connecting to the voIP system from my smarphone with a voIP app, in order to answer phone when not at home.
An answering machine would be great too.

Any system that can do that, easy to use?

I agree, that is the reason why I opted for a dedicated VoIP base station, one thing less to worry about when updating the router.

Yes there are so called ATA (Analoge Telefon Adapter) that allow you to continue using old analog telephones as "hand-sets" the ATA will then convert the analog into digital SIP/VoIP. I have no first hand experience with any of those devices and hence can not recommend anything, but googling for ATA viop shiuld give you plenty to choose from.

As I said, no first hand experience with most of your requests (except my base station contains an answering machine which works as expected)....

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Lets see if somebody has experiences with adding a voIP centralite.

I think there are solutions based on linus with SOCs like RPi.
May bee you need an usb dongle to provide analog output or just use another LAN port (not very good option) and the converter you mention.

If you use only an ATA converter, then I suppose you have to configure it with the SIP server provided by your ISP and you then have phone but only in the analog phones, with no posibility of answering from other phones, or at least that is what I understand.

Yes, all models with integrated DECT CAT-iq 2.1 and FXS ports do support being configured as ethernet client (IPoE) behind an OpenWrt router. Personally I'm using a 7430 jailed into its own VLAN/ firewall zone in that capacity (you only need to configure that it actively keeps the SIP connection open, to deal with NAT); to get the maximum support cycle, one should opt for a (small, but-) current model though.

That works pretty well for (up to) 10 SIP phone numbers, up to 6 DECT CAT-iq 2.x handsets (directly registering to the Fritz!Box), several dedicated SIP phones (Cisco and Grandstream in my case) and an analogue Fax machine connected to the FXS port (two available on bigger models).


Yes, for something like that you need an integrated base station that itself supports the number and type of phones you want to use and also supports internal hand-over/internal calls and what not. I am certain there are instructions to be found how to build something like that with mostly open-source solutions/components. But due to lack of interest and time I never tried and hence hope the same as you:

Good luck!

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It sounds good.

I currently have a Fritz!box 4040 as my router with DNS, mosquitto, and DHCP server and AP to the salon and near rooms. I have installed openWRT in it.

It is a nice looking device and it works well. But has no DECT or other option for voIP.

There is an ADSL router with Dect from AVM (7350 I think) ¿Are you refering to that?
¿Or are there other device that just provide access to voIP?
OpenWRT does not fully support it, no DECT or other funcionality, but the propietary firmware should work.

Is it possible to connect to it using a smartPhone voIP app?
From outside.

It should be possible fro sure using an VPN, but for receiving phone calls in it, a more direct connection to the internal voIP server would be probably better (with appropiate rules and firewall settings):

The 7520/ 7530 (or even the 7510) would be the natural successor of the 7430 I've been using for the last couple of years (7590 if you need two analogue FXS ports), using VPN (configured in your OpenWrt router, wireguard recommended) would allow hooking up your SIP (smart-) phones to that SIP pbx. The network topology would be:

          [ - OpenWrt router - ]
      /         |         |       \
[desktop]  [smartphone]  […]  [Fritz!Box]
                            [DECT handsets]

Similar setups would be possible with SIP DECT bases as well, SIP phones could also connect to your ISP directly (although it makes sense to register them to your local SIP pbx, for internal calls and better integration into the system as a whole). I would assume that several other VoIP routers would offer similar functionality as well.

Instead of a VPN from the main router to the fritzbox, wouldn't it be the same with a VLAN?

The SIP data comes throuh VLAN 2 and can be redirected to the fritz in the same vlan in order to isolate it from other devices in the lan or other local lans...

It is a pity I don't have it in my current fritbox to be able to test it.

Does it have an rj11 connector in order to use other phones at home?

If I understand you well, the Fritzbox will act as a DECT base and you can connect other DECT phones to it.
I have two of them now, one being the base connected to analog line. I suppose I have to deactivate that base and make it act as a DECT slave of the fritzbox.
Great, that is one clean solution. But I will need to change my secondary router.

Before spending more in it, I will try to install a software centralite to see if I am able to configure a DECT system and all the SIP config.

Thank you.

The smaller models have one TAE-6 port, the larger ones two; TAE-6 is a analogue phone plug specific to the German market, but there are cheap mechanical adapters to rj11.

Please check your ISP's exact SIP requirements for compatibility - and keep in mind that there are plenty of other alternatives as well.

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Great, thanks, it seems like a good option.
Have to see price and other constraints. But would substitute the current fritzbox nicely.

OpenWRT does not work with its DECT system.
But as I will replace its current funcions by another main router, and it will just remain as a Wifi AP and switch for the devices connected with ethernet to it, it would be posible to just use the original firmware.

I don't want to use any cloud service or register the device with AVM.

Is it possible to use it without having to depend on AVM servers?
I remember that the original firmware offered such options.

Does the original firmware have VLANS and can be configured?

I will need VLAN to be able to route the voIP traffic from the main router and the normal IP lan traffic to it throguh the same wire.

There is no DECT support in Linux, <fullstop>. If history teaches us a lesson, this isn't going to change in the future either (there was functional proof of concept code in the past, but it never went anywhere). For SIP, ATA and DECT services you'd need to keep the OEM firmware.

Not necessary.

No, respectively only in the most minimal form to support basic VLAN tagging on WAN (use your OpenWrt router to do the necessary VLAN transformations, however the 4040 (ipq40xx) is a bit challenged in that regard).

I doubt that this is going to work.