VDSL modem/router with VoIP capability


#1

I'm not sure this question actually belongs in this forum - or in this site at all.
If it doesn't, I apologize in advance, and I'd be glad if someone could suggest an alternative online resource where I could ask.

I'm considering switching from plain ADSL to fiber (FTTC), which would also migrate my telephony services to VoIP. My decision is almost done, but I'd like to have a plan for upgrading my home LAN and my in-house telephone network.

Networking

First, the router. I'd prefer an integrated modem/router if possible, unless it implies a lack of features/performance.

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?).
  • Good wireless.
  • 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.

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.

Telephony

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?

I'm planning on installing an Asterisk server, too. the uses I see now are telemarketer avoidance, in-house interphone use, smart integration of family smartphones into the house telephone network.

If necessary, I would get myself a small dedicated machine for Asterisk - I'm thinking of a micro-server running some form of linux, probably ubuntu. Is it easy to interface an external server with the router, or am I better off running Asterisk directly on the router?

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?

#2

With those requirements, you will have to go with (3) dedicated devices for modem, router and sip ATA.

The only OpenWrt supported SOC with VDSL support is lantiq VR9 (VRX268/ VRX288), which is fine up to profile 17a, 30a - however it doesn't support super-vectoring (VPlus/35b). The newer xRX3xx/ xRX5xx lantiq chipsets which could support it aren't covered by OpenWrt yet. Furthermore as a SOC, the lantiq xrx2xx chipset isn't the fastest (especially without proprietary hardware acceleration), which would be limiting towards the upper end of your expectations (if you want to go this route, the BT Home Hub 5 Type A is as good as it gets). So if your requirements are set in stone, you will have to use a dedicated (non-OpenWrt) VDSL modem.

There are plenty suggestions for highend routers, so I don't think that question needs to be repeated here.

In terms of SIP support, you can look at lantiq VR9 again, which has FXS support under OpenWrt via asterisk and chan_lantiq - or you could dabble into commercial offerings, native SIP phones, etc.

Yes, with somewhat adjusted expectations you can do all three tasks with OpenWrt supported devices - but performance and the available selection of supported devices won't be sufficient to do it in a single device (with one core lost to voice processing/ FXS support, effective WAN throughput on lantiq VR9 with OpenWrt is limited to roughly 55 MBit/s).

For practical reasons (performance, feature and security), using a dedicated NAS type device would also be a better choice, but highend mvebu or ipq806x might also do a decent job there.


#3

Thanks for your reply, @slh. I've spent the little free time I've had this week researching the market a little.

It appears that pure modems suitable for OpenWrt are not very common. Would you have any suggestion? And would a separate modem (rather than an integrated modem/router SOC) mean more latency?

I didn't understand your tip about NAS devices. I do have a couple of NAS units running, but I use them for storage/backup only.

One more question about Asterisk: if I decide for a separate Asterisk server (something like a small 4-core, the size of a book), will the ATA line outs need to be on that server, or can I use the router's line outs, if it has some? Sorry if the question seems newbish. It actually is, because I've got no idea about the data/audio flow between SIP/VoIP devices. Any pointers to suitable introductory material will be welcome. Thank you for your patience!