VoIP and ADSL on the cheap?

March 10, 2006 10:17 PM

What's the minimal hardware I need to put my house phones on VoIP?

Background:

ADSL has finally arrived in our little village this week, and I've signed up with an ISP that offers very attractive bundled VoIP pricing and a good reputation for helpful support. I'm expecting my line will be ADSL-enabled within a couple of weeks.

I want to set up my shiny new broadband connection with the least possible expenditure on new hardware, while at the same time getting my house LAN arrangements in order. I've got an old PC with a huge disk drive that I've been meaning for some time to set up as an always-on Linux-based server.

I know how to make that work as a NAT router/firewall and file server, and I'm sure I can work out enough of Squid to speed up my Windows updates and present a useful work-around-the-filters challenge to our nascent 14-year-old hacker, but I have no experience at all with ADSL modems or VoIP adaptor boxes. I'd like to hang one of each off of the server.

Questions:

1. Given that my ADSL connection will be PPP-based, that I do already have an old 10mbit Ethernet card I'm not using, and that there are unused USB 1.1 ports on my server PC, is there any reason to prefer an Ethernet-connected ADSL modem to a cheaper USB one?

2. Is it feasible to press my old 56K external voice/data/fax modem into service as the hardware component of a VoIP adapter for my existing house phones? If not, why not? If so, what software will the server need to simulate what the ISP's recommended VoIP adaptor can do?

3. Why don't I just use the wonderful Product X, which has an inbuilt POTS/ADSL splitter, plus an ADSL modem, plus a house phone interface that allows incoming and outgoing calls via both POTS and VoIP (selectable per phone number and/or by dialling prefix and falling back to POTS on power failure), plus a NAT router, plus an easy-to-use Web-based configuration tool, plus endlessly upgradeable open-source firmware, and costs not much more than a vanilla ADSL modem?

posted by flabdablet to computers & internet (15 comments total)

1. Yes. You will need to hook the VOIP adapter up to the DSL modem and the VOIP adapter will need Ethernet. So, you will need the Ethernet modem.

2. Ask your ISP, but probably not, as your ISP is probably not going to tell you how to set up a SIP client. The modem wouldn't have anything to do with anything anyway. If you were using a PC as a VOIP adapter you'd use a sound card to get the audio in and out, not a modem.

3. You wish.
posted by kindall at 11:07 PM on March 10, 2006

You will need to hook the VOIP adapter up to the DSL modem and the VOIP adapter will need Ethernet. So, you will need the Ethernet modem.

I'd envisioned connecting an ADSL modem to my Linux box via either (a) a dedicated network card (my currently-unused 10mbps one) or (b) a USB port.

The Linux box would have a separate 100mbps link to my existing Ethernet switch, and run DHCP to manage it; I thought I'd then be able to plug the VoIP adaptor into any port on the switch.

Wouldn't this arrangement make the ADSL< ->Linux box connection method moot as far as the VoIP adapter was concerned?

probably not, as your ISP is probably not going to tell you how to set up a SIP client.

Is there more to it than this? Because that looks pretty straightforward.

If you were using a PC as a VOIP adapter you'd use a sound card to get the audio in and out, not a modem.

My thinking was that a voice/fax/data modem would likely have some kind of usable codec built in, plus be designed for POTS-compatible signal levels, plus have all the switching gear needed for various operational modes... but now that I'm actually looking at the thing, I see that it only says "56K fax modem" on top. Bugger.

You wish.

The ISP provides configuration info for the Billion 7402VGP, which looks like it does just about everything I mentioned except be cheap. Anybody know any particular reason I might regret spending AU$259 on this toy?
posted by flabdablet at 2:38 AM on March 11, 2006

(Sorry this doesn't directly answer your original question)

I got set up with Internode's Nodefone (using the SPA3000 connected to my not-very-new Draytek modem-router) just a couple of weeks ago -- it's the cat's pyjamas!! If I were starting from scratch again I'd definitely go with something like the Billion 7402VGP.

I'd suggest you do your sums to work out how much you will save on your regular phone bill with ADSL and VoIP, then look at your options from there regarding set-up costs. You may find the savings over a fairly short period justify the initial outlay of an all-in-one solution... or not. Also, check out the VoIP forum on Whirlpool for some friendly advice on hardware options -- there are quite a few Internode customers not using Nodefone as well as many who are, so it's a great place to get info on all the options available to you.

Good luck with it!
posted by harmless at 3:40 AM on March 11, 2006

I have VOIP running through my house wiring and it's very easy. I have a cable modem. The Vonage supposed VOIP-enabled router connects to that. I have two computers and a WiFi router connected to that, and a phone lines also comes out of it. I just plug that into the wall, and voila, every other phone jack in the house now has a dial-tone and works normally.

WARNING! Make sure you are disconnected from the telephone company before you do this. I disconnected myself on the box outside my house, just unplugging a regular telephone plug at the box.

Make sure your isp is REALLY giving you a good deal. My ISP offers it, but it's the most expensive VOIP alternative, and doesn't even include voice mail in the standard package.
posted by JamesMessick at 4:26 AM on March 11, 2006

If you use the integrated box, it's going to be easiest. Most (all?) of them have QoS features, where they prioritize your voice traffic over anything else. This makes your line work better when you're downloading things.

The major downside to most of the integrated boxes is that, generally, they're not quite as flexible/powerful as standalone devices would be. But it doesn't sound like you're that advanced. Unless you're the type that spends many hours figuring things out, and you want to take total control of how your network operates, the integrated solution is likely to be better for you.

To roll your own, you'll have to figure out:

A)How to connect the ADSL modem to the Linux box(easy);
B)Linux PPP (at one time quite hard, not sure these days);
C)Linux routing (pretty easy);
D)Linux NAT/firewalling (hard);
E)How to connect a SIP client (rather involved);
F)How to get QoS working (damn difficult)

Unless you're really into this stuff, AU$249 isn't that bad. :)
posted by Malor at 7:13 AM on March 11, 2006

harmless: thanks for reminding me about Whirlpool. Lots of good stuff over there.

malor:
D) I've done successfully before.
E) I've been looking at Asterisk to handle the SIP stuff; it looks doable.
F) Hmmmmm.
posted by flabdablet at 7:48 AM on March 11, 2006

Go with option 3. I tried the earlier route of setting up an older machine as a Linux router and, while successful, it was far more maintenance.

Do yourself a favour, pick up one of these (make sure it is not a v4 or v5) and flash it with this firmware.

You'll essentially have a mini-Linux router that is extremely stable, easy to manage (through either command-line or web) and will provide all of the features you're looking for once flashed.

Stick with the modem provided by the ISP (support issues if you go with unsupported hardware) and put the router directly behind it. Plug in the VoIP router and your machines and attach this phone (or similar) to the VoIP router. You only require one base and wired connection and all the satellite phones operate independently.

Total cost (aside from charges from the ISP) should run you about $150 but you'll save hours in configuring, wiring, and just general headaches.
posted by purephase at 8:29 AM on March 11, 2006

Well, if you think you can handle Asterisk, then using the Linux box to serve all your purposes at once does make some sense. A few things to think about:

A) You'll have to carefully maintain patchlevels on any box exposed to the outside world.
B) Separating your firewalling from your other services is a very good idea, from a security perspective.
C) If you buy the integrated box from your provider, it becomes their responsibility to maintain. Hacks against these things are pretty rare (at least, I've never heard of any), but should something come up, it's up to them to fix. This can be a plus or a minus, depending on how responsive they are.

If you like tinkering, definitely go for doing it yourself... you'll learn more, and you have absolute control. As long as you're okay with the ongoing maintenance time cost, go for it!

I don't know a lot about Asterisk, but everything else you can probably do with your existing hardware. If you want Asterisk to work like a normal phone (as in, you have handsets all over the house you can just pick up and use), I tihnk you'll need some kind of bridge hardware to tie into your POTS lines. (POTS = Plain Old Telephone Service). You'll also need to disconnect those lines from the outside world. The POTS-bridge devices will power your local phone lines, but if you're connected to the outside world too, you're likely to fry something.

The fact that you have the service coming in on ADSL complicates matters... you can't just disconnect all the wires coming into your house, or the ADSL won't work! Hopefully, you will have two wire pairs in your house.... most American houses have at least two.

I'd probably run the ADSL in on the second pair, disconnecting the first pair from the outside world. Then use your Asterisk-to-POTS bridge device to talk to the first pair. This lets you plug in standard phone equipment, without rewiring any internal house jacks. (You may have to rewire the jack where the ADSL actually comes in, though.)

If you have only one pair, you won't be able to use it for VOIP phoning at the same time as your ADSL link... you'll need another solution.

What I do, with my Vonage phone, is just run a two-handset cordless straight off the back of the Vonage device. Problem solved.
posted by Malor at 8:42 AM on March 11, 2006

A) I was thinking of running Ubuntu, which has a nice auto-updater, but perhaps IPCop would be a better starting point?
B) I'm pretty happy with the degree of separation caused by having WAN and LAN ports running off different network cards... of course I'll change my tune the first time somebody uses an Asterisk flaw to bust my firewall :)
C) The ISP's price on the Billion box vs. the going rate from my favorite discount retailer represents pretty bloody expensive insurance.

I already have a cordless phone, so that's no biggie. Also, I'm in Australia, and I put most of the phone cabling through this house myself; fiddling about with it shouldn't be problematic, and having once worked for a company that supplied hardware to telcos, I'm confident I won't fry anything.

The Linksys router looks cute and I've heard good things about it before, but I don't really need wireless (just another security hole to attend to, AFAICT) and it doesn't have inbuilt ADSL or VoIP so I don't think I'll bother.

So now all I need is an Analog Telephone Adapter with power-loss failsafe and a nice Ethernet ADSL modem (without router). Anybody have favourites?
posted by flabdablet at 10:00 AM on March 11, 2006

Having the separate LAN and WAN ports, in and of itself, won't give you much (if any) protection. It would be awkward to do firewalling any other way, in fact. It probably could be done on a single physical network connection with aliasing, but it's just.... so wrong.

If you configure most of your services to listen only on the LAN port, that would help more. You won't be able to completely firewall your WAN link, because you have to accept inbound SIP, at the very least. I'd suggest accepting ONLY the SIP ports... block everything else inbound, including ping and ssh. Set up SSH on your firewall with a public key, rather than a password... there are many dictionary attacks going on. I have a server that gets hit hundreds or thousands of times a day with dictionary cracking attempts. It doesn't accept passwords for authentication, so it's immune.

Personally, having been a sysadmin for a long time, I get nervous about putting critcal data on boxes exposed to the outside, _especially_ if I'm running a service (like Asterisk) that I don't understand well and might misconfigure.

You should be okay with just one machine, but back it up regularly and watch for funny behaviors. You may not want to use it for a fileserver... I'd suggest storing files elsewhere. (the Linksys NSLU2 is a good cheap NAS device... about $80 for the box, and then an external USB2 hard drive.) And make sure the passwords on the firewall/Asterisk box are different than anything else in your network, and don't set your other machines to trust that one in any way.

If you do those things, you should be pretty safe. Ubuntu is a fine distribution, very clean and easy to configure. It's based on Debian, which is what I always run on my Linux servers. IPCop will probably be configured much tighter out of the box, though, since it's aimed at being a firewall, rather than a general-purpose distro. But it will probably be much harder to get Asterisk running.

You're probably not after military-grade security. Most likely, you're just trying to make yourself a difficult target, so people won't bother with you. :) Ubuntu should be fine, and it's very easy to update.
posted by Malor at 11:09 AM on March 11, 2006

Oh, and as far as your hardware requests go.... I can't help you there. Hopefully some Australians and/or Asterisk people will chime in with what you need.

You could always ask your ISP what standard they use for DSL... that would help you shop.
posted by Malor at 11:11 AM on March 11, 2006

flabdablet writes "The Linksys router looks cute and I've heard good things about it before, but I don't really need wireless (just another security hole to attend to, AFAICT) and it doesn't have inbuilt ADSL or VoIP so I don't think I'll bother."

The wireless options available in the HyperWRT firmware are about as secure as you can get (provided you use WPA2 and Radius) and it's really not that difficult to setup. The firmware also has options for ADSL (PPPoE) and QoS for VoIP services (I use it extensively). Believe me, the aftermarket firmware development for these routers has produced some incredible results. If you're interested in more in-depth capabilities (and you want to play and/or learn) then check-out the OpenWRT project.
posted by purephase at 12:48 PM on March 11, 2006

Purephase: When I noted that the WRT54GS "doesn't have inbuilt ADSL or VoIP" I was talking about interface hardware. I'm sure it does an admirable job of supporting SIP and all the ADSL-related protocols in software.

On software: given that the OpenWRT firmware is based on a writable file system - effectively making it Just Another Linux Distro, and one based on a 2.4 series kernel at that - why would I choose to spend money buying the cramped hardware it's built for rather than run the latest Ubuntu on the far more capable hardware of a spare PC I already own?

Surely whatever facilities OpenWRT is using for QoS are built into the Linux kernel and therefore, by definition, available to any Linux on any platform? And isn't it likely that the QoS stuff in the 2.6 series kernels will work even better than the 2.4 series?

Also, ISTM that security-wise, a router with a writable flash file system is no more inherently secure than a PC with a hard disk in it. Your thoughts?

Malor: do I really have to accept incoming SIP connections? From the limited reading I've done so far, I understand that SIP clients are supposed to Just Work behind NAT routers - which suggests to me that it's the SIP client that initiates connection requests to the SIP server, meaning I don't have to poke holes in my firewall unless I'm trying to set up my own SIP service.

I don't envision needing any services listening on the WAN port at all, at least at this stage; I have no need for SSH from outside (and my ISP doesn't give me a fixed IP address on this cheapo plan anyway, meaning I'd have to fart about with DynDNS if I did want remote access).

It also seems to me that Tripwire should give me more than enough intrusion-detection peace of mind. As you say, this isn't a military facility, and my media collection isn't a state secret.

Thanks for the ideas, people - I'm starting to feel I have enough of a grip on this thing now to know what questions to ask. Keep 'em coming!
posted by flabdablet at 4:12 PM on March 11, 2006

flabdablet writes "Purephase: When I noted that the WRT54GS 'doesn't have inbuilt ADSL or VoIP' I was talking about interface hardware. I'm sure it does an admirable job of supporting SIP and all the ADSL-related protocols in software."

Definitely, no interface hardware.

flabdablet writes "On software: given that the OpenWRT firmware is based on a writable file system - effectively making it Just Another Linux Distro, and one based on a 2.4 series kernel at that - why would I choose to spend money buying the cramped hardware it's built for rather than run the latest Ubuntu on the far more capable hardware of a spare PC I already own?"

Noise, electricity use, the ease of setting-up and/or maintaining it for the future. There are more space requirements for a PC (provided it's not a shuttle) then a small router. Last, they're really not that expensive.

flabdablet writes "Surely whatever facilities OpenWRT is using for QoS are built into the Linux kernel and therefore, by definition, available to any Linux on any platform? And isn't it likely that the QoS stuff in the 2.6 series kernels will work even better than the 2.4 series? Also, ISTM that security-wise, a router with a writable flash file system is no more inherently secure than a PC with a hard disk in it. Your thoughts?"

Without looking at the changelog for the kernel I can't be certain that newer necessarily means better. Although, I can't make the case either way never having tested it. ;) As for security, I believe that unless you really know what you're doing, a smaller device (less disk space) specifically designed for this one function would probably be a little more secure than a full-fledged server.

As an aside, you can setup Asterisk on an OpenWRT installation.
posted by purephase at 5:32 PM on March 11, 2006

Noise and electricity use are fair points, but my old PC isn't particularly grunty and doesn't need much fannage, so I think those issues will be more than manageable.

As for setting-up and/or maintaining it for the future: I'm still thinking I'd be better off not having to worry about running out of RAM or flash space; and by the time the general run of router hardware has comparable performance to my old PC, I will likely have another obsolete PC available that's an order of magnitude bigger and faster and trivial to migrate my existing software setup to. I don't see that being so likely to be true of proprietary, non-commodity router hardware.

The Asterisk setup link is really useful - thanks - and there's a paragraph there that's pretty much convinced me a PC is the way to go:

Memory and storage are the two big constraints on Asterisk on OpenWrt. A voice mail module is available, but with such scarce resources for storage, I opted not to use it. Running a second or third line would also be expensive in terms of memory, and might be more than OpenWrt could handle.

In my opinion, Asterisk on OpenWrt is a fun experiment, a good way to learn about telephony, and an easy way to learn Asterisk. But I wouldn't want my small business, or even my home office, to depend on it for voice communications.

As for security, I think I understand the tradeoffs involved well enough to get by.

Asterisk@home looks like it was made for this job, too.

Thanks again to all. I love AskMeFi!
posted by flabdablet at 6:41 PM on March 11, 2006