VDSL modem/router with VoIP capability

I made a similar question just over a year ago, but there wasn't yet an integrally OpenWrt solution, so I procrastinated. Now I can't defer anymore. I don't want to fell prey to proprietary solutions, so I need some advice. I live in continental Europe.

I have to switch from plain ADSL to fiber (FTTC), which would also migrate my telephony services to VoIP.


First, modem and router. I'd prefer an integrated modem/router if possible. However, I've read up and found that powerful modern integrated hardware isn't friendly to open source, so I'm open to a proprietary modem.

My new modem should support current ADSL/VDSL standards (8b, 17a, VPlus/35b), as well as retransmission (G.998.4), vectoring (G.993.5) and SRA (G.993.2).

My new router should have

  • At least 4 gigabit ethernet ports for LAN (plus 1 for WAN if the modem isn't integrated).
  • Probably at least a couple analog ports for the phones (or is there any sort of external box to make up for lack of analog ports?).
  • Decent wireless. I have repeaters around, so max power isn't a requirement.
  • At least 1 USB port for drives etc (2 would be better).
  • I'd like a fairly powerful router, with plenty of flash memory and RAM so I can use/experiment with all the packages I fancy without too many memory/CPU constraints (e.g., Asterisk).

And of course, it should be a device where OpenWrt is known to work and easy to install! Installing OpenWrt is the first thing I will do when I unpack it.


As for telephony, I have traditional (analog) phones all around the house, and while the next phones I'll buy will be presumably VoIP, in the meantime I'd like to keep that analog network going. Will I need additional hardware for that?

As an extra, I'm planning on installing an Asterisk server, too. The use I foresee is telemarketer avoidance, in-house interphone use, and smart integration of family smartphones into the house telephone network. Not sure if I can run Asterisk on the router (which would then need POTS interfaces for my old phones) or I need an external box. I'm open.

My would-be provider uses the following codecs:G.729, G.711 A-law, G.722, T.38 (for facsimile). I don't know if this is relevant for choosing the hardware, but I don't know anything about VoIP, so I'm providing all the info I have.

Bottom Line

  • What's your advice for a suitable router/modem solution?
  • Should I get a dedicated server for Asterisk?

A wise man once said: "you can't have everything!"

This seems particularly true with OpenWrt and xDSL, due to unavailability of drivers.

There is already a very small number of supported xDSL modem-routes. So with your other more essential requirements, you will have to drop the xDSL requirement.

Thank you for the reply, @Hegabo! A proprietary modem would be OK. Which one would you advise?
The router will just need to have an extra gigabit ethernet port for the WAN, I guess.

Well, usually ISP all-in-one devices should be fine (if it's supplied recently) as long as you can set it to bridge mode.

Do you actually need gigabit WAN speed?

You probably should mention your budget, because gigabit WAN + telephony, there might not be many options.

You're right! Gigabit WAN is not necessary. It's FTTC, so the maximum rate should be around 200 Mbit/s up/down if I'm not mistaken. As for the budget, I'm ready to spend as much as it takes - within reason. A few 100's of euros, I suppose? Not sure if I need a separate VoIP server or not, the necessary interfaces etc.

The function that connects analog phones to a VoIP service is called an ATA (Analog Telephone Adapter), or more specifically a SIP to FXS adapter. These are not expensive as a separate box.

To have the equivalent of a conventional analog phone line, you do not need to run a server such as Asterisk locally. The ATA connects to the third party service directly via the Internet.

Thanks @mk24, I learned something from your answer! I have 2 questions.

  1. From your answer, it seems I would only need an ATA connected to my router (or Asterisk server in case I have one) via ethernet and to the telephone wall socket via a phone cable. Would a single ATA, plugged where the analog main phone is plugged now, be able to deal with all the analog phones in the house?
  2. I understand I don't need Asterisk to duplicate the current (plain) functionality. But I'd like to be able to do call filtering (for example: not ringing my phone until the caller has dialed a certain menu item), answering machine, in-house extensions etc. Would Asterisk allow me to do all these things? I do have a working knowledge of the Unix OS, TCP/IP etc., and I'm ready to learn how to configure and run the beast.

Yes you can connect (within reason, say up to 5 sets) multiple phones to one FXS port of an ATA, using conventional parallel wiring. They will act the same as connected to one analog line, that is only one conversation at a time and eavesdropping is possible by picking up one of the extensions. Typically that installation is made by disconnecting all the phone wiring in the house at the phone company demarcation, then back-feeding a phone jack with the ATA.

If you're running your own PBX you probably want to migrate to IP phones sooner rather than later. I have some experience with FreePBX, which is Asterisk with a GUI front end. It works well on any mini-PC, I'm using about the lowest end such PC, a "Wintel Pro." There are also other PBXs like FreeSwitch and YATE.

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Two, perhaps[0], but not five. Common ATAs are marginal in terms of the voltage and current they provide, whatever the (SOC-)vendor thought they could get away with - but always less than 'real' POTs (and 50 Hz, instead of 25 Hz, which is another problem for electro-mechanical ringers). The more phones you add (in parallel), these issues increase and becomes more emphasized - with five phones, you're pretty likely to miss calls.

If you're living in Europe, the O² Box 6431/ Arcadyan VGV7510KW22 might be an attractive device, which is supported by OpenWrt and provides two (supported via asterisk16-chan-lantiq) FXS ports - this works nicely on OpenWrt. Sadly the device itself is a bit low-end, but it's cheap (5-10 EUR) on the used market. It works decently as a SIP pbx/ ATA, running OpenWrt and asterisk - XOR as a simple VDSL2/ vectoring (up to profile 17b, but not 35b) modem, but not both; and it isn't really a good router/ AP either.

[0] but you don't want to connect multiple phones to a single ATA port, as that wouldn't allow internal connections between the phones - and parallel phones would allow eavesdropping.

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Thanks again, @mk24 and @slh. I am getting there.
Given the suggestions, I'm oriented towards:

  1. A used O2 Box 6431 (OpenWRT+Asterisk) - to use as ATA only.
  2. A used VSL2 modem/router that supports 35b and whose OEM software allows bridging mode - to use as modem only.
  3. A future-proof (new?) router, fairly powerful, with 4 gigabit LAN ports and plenty of Flash/RAM. Here I definitely want to go OpenWRT. I am used to make my own images on a Ubuntu host, so I can easily compile any selection of packages if it can be done easily with menuconfig.

Suggestions for 2 and 3?

There are only few options, Dartek's vigor165 seems to allow operation in bridge mode and profile 35b (while being lantiq/intel/maxlinear and not broadcom).

If you don't need profile 35b right now, I'd skip this requirement for the time being. Plain (used) vectoring (up to profile 17b) VDSL2 modems sell for a dime a dozen (under 10 EUR plus shipping), even a selection of OpenWrt compatible ones (e.g. the BT Home Hub 5 Type A, which regularly goes for around 8-9 GBP plus shipping). Profile 35b capable ones however are in a quite different price range, e.g. the afforementioned Draytek Vigor 165 for around 140 EUR (new).

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All right, I think I'll drop 35b for the time being.

As for the BT Home Hub 5 Type A you mention: it looks fine, but at the moment they only ship from the UK on eBay, which is slightly inconvenient because of the bulky, incompatible power connector as well as slightly more expensive shipment. Any other suggestions? OpenWRT is a plus, but not a requirement, as long as bridging is possible from the OEM management interface.

Now I only need some advice about the router, and I'm ready to call my Telecom/ISP :grin:

By the way, the interaction with this forum is really helping me understand/redefine my needs! Thank you.

I've placed bids on eBay on both a BT Home Hub 5 Type A (candidate modem) and an O2 Box 6431 (candidate ATA). The wall plug adapter for the BT Home Hub is likely to cost me almost as much as the box itself. Maybe I'm getting a compatible power supply with EU plugs instead. :laughing:

So all that's left now:

Any advice on a good, easily OpenWRT-able router? I would like it to have

  • At least 4 gigabit ethernet ports for LAN (WAN port could be 100 Mbit/s, but in perspective it'd better be gigabit as well: when VPlus/35 arrives in late 2020/early 2021, I'm going to get a new modem.
  • Decent wireless. I have a few dumb APs around, so max power or smart coverage isn't a requirement.
  • At least 1 USB port for drives etc (2 would be better).
  • Plenty of flash memory and RAM to stay reasonably future-proof

DSL/modem functionality is not required, obviously.

The PSU is not the issue, that's really bog-standard at 12V 1.5A. The problem is the barrel plug at the end of the cable. The HH5A is using an usual connector: 6.3mm outer diameter, 3mm inner diameter, 11mm length.

I went ahead and fixed myself an adapter by cutting off the barrel plug with some length and soldering a standard 5.5mm x 2.1mm female plug to the other side. Now I would be able to use one of the two dozen 12V PSUs laying around (I'm using the subjunctive because my HH5A has developed a loud high-pitched whine that makes it unusuable in living quarters.)

But then again you can just get an electrical adapter for ~€2 and call it a day.

Okay, now I'm slightly confused. The HH5A is and does all of that if you're willing to go through the (admittedly nontrivial) process of flashing OpenWrt to it.

Yeah. Me too.

If your ISP provides you with a modem, or if you can just buy a used modem from the local market or get one from a friend, then that should be fine and much easier.

It just doesn't make much sense to get into the trouble of flashing BT Homehub 5A with OpenWrt (and believe me, trying to get serial connection can be frustrating) just to use it as modem, and you can't use it with a third party ISP without flashing it (I think), and it might not give you the speed you want of you use it as a router (not sure about the maximum speed to be honest).

(I'd written a reply to @takimata's post, before noticing @Hegabo had chimed in, too. I extended it.)

@takimata, The cheapest electrical adapter Amazon will deliver within the month costs nearly 9€ when you include shipment (none available with Prime free shipping).

That's why I'd also looked up a Chinese PSU that features interchangeable barrel plugs, including the so-called Type B (6.3-3.0 mm) and promises 4A @ 12V for under 8€.

As for the router, for some reason I'd just assumed the HH5A couldn't cope. Maybe I'm just being dumb. Thank you for waking me up, really. :blush:

(Was it actually that hard to reflash?)

@Hegabo My ISP doesn't provide me with a modem. They only sell mid tier all-in-one boxes that can't be upgraded to OpenWRT.

So you too suspect the HH5A might be unable to cope. On the other hand, I thought it'd be easy to reflash - easy enough to justify doing it 'just because I can' - also, I would be able to view/change the DSL parameters, and I would be sure it can be configured as a pure bridge. One of the HH5A's on eBay does have OpenWRT 19 already loaded anyway. I'm bidding on that one now.

I suspect I'll have to reflash it anyway: I prefer my own choice of packages to be integrated in the image, and I have a build system already up and running for other targets.

Maybe the best course of action could be just wait and see if I win the auction for the open sourced HH5A and see how well it does. What do you think? Any alternative hardware suggestion will be most welcome.

I'll need sqm to deal with Netflix and VoIP. and I have an unusually long list of MAC addr matching rules in the firewall (using ipset). At present, my old Buffalo WBMR-HP-G300H manages at ~7 Mb/s, with a healthy amount of free RAM - but I suspect the CPU is nearly maxed out in some situations. On the new router, I wouldn't mind trying to set up a Tor WAN interface in addition to the plain one.

@bill888 can hopefully tell you how much speed you can get from the BTHH5A. I am using it but my max line speed wouldn't let reach the maximum speed of the device.

Innitial flashing is hard, yes. You have to make a serial connection using a TTL adapter, and the points you need to connect to are very small.

Reflashing should be easy, as you would not need serial connection for that.

Though, to buy a flashed device and get it shipped to Europe would probably cost you around 20 to 25 euro. Add to that say 5 got the adapter or plug converter. It makes sense if you are going to use it as a router. Otherwise, I think any ISP modem should be fine.

As suggested by @Hegabo , it would perhaps be better to try and find a cheap modem in your country which support bridge mode. eg. Netgear DM200 or TPlink TD-W9970, and then use it with a more powerful (openwrt) router of your choice.

Your original list of requirements included support for USB drives. HH5A wouldn't be my first choice for USB if you intend to use it as a 'router'.

I am pretty confident that you would not be happy with the HH5 as all in one router under OpenWrt. In my limited testing it could not manage to to do sqm, may, pppoe, firewalling, WiFi, VDSL 50/10, all at the same time. It is now operating as bridged modem (under OpenWrt, bought it preflashed on eBay) on a vdsl2 100/40 link, and is capable of delivering that speed to my router. Depending on your load you might try it as a all-in-one router first, but I predict that it is not going to be fast enough, given your list of requirements.