VOIP & Asterisk

I work in an open-plan office. Normally I like to listen to some of my iPod's music, or NPR or something, at some point during the day. It helps me tune out distractions when I'm coding or concentrating on something. My iPod, and my nice Etymotic headphones, get transported to and from work each day in my laptop bag. Today I forgot the laptop bag at home.

What to do? I could just work without headphones. I'd be fine, but you know, I've got standards here. My job involves working with computers, so I ought to be able to come up with a workaround, right?

So lesse... what do I have? One binaural (mono sound, but speakers for each hear) telephone headset. One Polycom SIP phone, connected to our corporate Asterisk system. One workstation with sound capabilities. One installation of Asterisk on this workstation for testing purposes. And, a pre-existing path from the corporate system to the workstation system for testing Asterisk. (Very handy that, and used a lot when we were doing active Asterisk work.)

So in less then five minutes I had music going via my telephone headset. Lo-fi, and not noise-dampening like the Etymotics, but I enjoyed it for the simple fact that it was being played *over the phone* at no cost to anyone. My desk phone supports multiple "lines", so I still could place and receive calls just fine.

Should anyone care to look, they'd find a 5-hour call from me to myself deep in the Asterisk logs. My own workstation logs will show that I put myself on hold for 5 hours (since I used Asterik's music-on-hold feature to play my own selections).

IP telephony is fun. So is Asterisk.

Issue 13 of Free Software Magazine is out, and it includes my article Asterisk: The Software Phone Company. If you're interested in running your own PBX in software, check it out.

It's been a little while since I wrote about Asterisk. It's about time to update the story.

I've been using Asterisk at home for awhile, but now we're going to use it at work.

The need

We have approximately 150 internal extensions here, and they are being supported by a Nortel PBX. This PBX is being end-of-lifed, and it would cost well over $100,000 to replace it, once the cost of the two required Windows servers (!) was factored in. Not only that, but it still isn't as flexible as Asterisk.

Along with that, we have a need for internal wireless phones. We have a large manufacturing area, and we have people that would like to be able to use a wireless phone anywhere on the shop floor or office areas. No single cellphone company provides a signal that is strong enough to reach everywhere in the building -- not to mention that there would be big airtime fees. So we are planning to deploy 802.11b wireless phones for this purpose.

Hardware

The decision was made to go ahead with Asterisk. We will be replacing all office phones with Polycom IP501 units. This means running about 90 new runs of CAT5 to people's desks.

For our Asterisk server, we got a HP DL385 2U server with dual dual-core Opteron 2GHz CPUs. We've really had good luck with Linux on these DL385s, and with HP's support. We got redundant power supplies, disks, fans, etc. on that machine. The CPU on here is probably more than we need, but telephones are very important to us and we wanted to make sure that we don't have any issues down the road.

We purchased two A104d quad-T1 interface cards with hardware echo cancellation. Very nice cards. The drivers have been a little troublesome. But Sangoma's tech support is awesome. They logged onto our box and I was watching as they were hacking on the kernel module right there. Tech support like that is rare. I highly recommend Sangoma.

We really need only one of those cards, but they're the only component of the Asterisk server that isn't completely standard. So the second is on hand as a spare.

For our analog phones, we are using two Adtran TA 750 channel banks. Each has a T1 interface and a 50-pin telco ("Amphenol") connector for a punch block. So we can run 24 channels off each of those. Our consultants (see below) suggested getting them used from Colspar Communications. We found them fully loaded with FXS cards for $250 each. We bought three -- two for production use and one for a hot spare.

These are very solid and nice units. The only problem we had is that the voicemail indicator lamps (MWI lights) on our old analog phones wouldn't light up. Turns out that Asterisk with a T1 channel bank uses digital FSK lamp, whereas our older analog phones expected a certain line voltage to indicate messages waiting. After some Googling, I found add-on FSK lamps from American Science & Surplus for $1.50 each. Nice.

In our other building, we have a gigabit fiber-optic link, so we purchased an AudioCodes MP124 SIP-analog gateway. It's working well so far, except it's not working with voicemail indicator lamps at all. It seems to be a firmware issue that is incompatible with Asterisk in some way. We're investigating now.

For wireless phones, we're using the Hitachi IP5000. We're not terribly pleased with the quality of wifi phones in general, but this one seems pretty solid. And it doesn't crash every few minutes like the Zyxel model we tried.

The Telco

Our current phone system has about 23 analog lines for interaction with the outside world. We wanted to get a voice T1 with PRI channel for the Asterisk system.

Our local telephone company is Sprint, and this has been the annoying part. First they tried to quote us an Internet connection. Then it took a very long time for them to even get us a quote for the voice T1. And now we have signed the contracts but are still waiting for an install date.

Consultants

While I had used Asterisk before, it was in a home setting. Not exactly business-critical, and not dealing with hundreds of extensions, T1 lines, and all the rest. So it seemed reasonable to get someone experienced with that sort of thing to help us out and make sure we weren't making mistakes that would cost us down the road.

I posted on the asterisk-biz mailing list describing what we would like to do. I got a bunch of supplies from consultants, and we wound up selecting Asteria Solutions Group. At the beginning, we wanted some advice about server sizing, phones that work well in business settings, etc.

I think that most consultants are not used to working with people that have significant Linux experience, and a good deal of Asterisk experience, already. Asteria was a little surprised with our situation at first, I think, but has been very helpful. They've educated us on the ins and outs of T1 technology, pointed us to Colspar (which saved us a ton of money on analog gateways), and helped us with some obscure questions. They were also fine to have a much smaller involvement with our project than they would probably normally have. I highly recommend them.

Surprises

You'll never believe just how hard it is to buy phones from Polycom. They won't sell directly to people, nor will they even list authorized retailers on their website. You have to call them, leave a message, and in a few days they'll let you know where to go.

Some online retailers such as atacomm sell Polycom phones, but they're not authorized to do so, so you don't get any warranty or have the right to get firmware from Polycom.

What's more, Polycom usually expects people to need configuration assistance with their phones. But I think that when I told them we need 90 IP-501s, had already configured 5 on our network, and needed no assistance, they were happy to work with us.

Reactions

We've deployed desk phones all over by now. So office workers have two phones on their desk right now (one from the old system, one from the new). We've heard a lot of positive comments from people about the new phones. And all the features of Asterisk -- music on hold, flexible queues, etc -- will be really helpful here.

Cost

Even with the cost of all new phones, new CAT5 runs and labor for that, consulting time, etc., we still expect Asterisk to be far cheaper than the latest Nortel PBX.

Also...

I recently wrote an article about Asterisk for Free Software Magazine. I'll let you know when/if it gets published.

So I've had this notion recently of running Ethernet from our basement utility room to several rooms throughout the house. This would let us use VOIP phones at several locations, among other things. My Grand Plan was to use the existing phone cabling as a rope. Tie one end to the shiny new CAT5e cabling, then go pull on the other one.

But it hit a big snag. Several, actually. Apparantly, the phone cables are stapled to the house's support structure -- INSIDE THE WALLS! I would have a punch multiple holes in the drywall to make this scheme work.

So plans must be re-hatched.

The shortest run is to the office, which is adjacent to the utility room. I've just been running Ethernet cables under the door for some time, and I'd like to put in proper jacks. The wall that the jacks should go on has -- yes, a phone cord in it, and yes, it's stapled. But to discover that, I had to enter the crawlspace above the basement ceiling and below the main floor -- a space about 1.5 feet high and not much more wide, and infested with all sorts of sharp pointy things (mostly nails), pipes, wires, etc. I only had to crawl about 10 feet but it took quite a while.

So, what to do? My dad suggested using a weighted chain, dropping it down the hole, then fashioning a hook to catch it from the existing electrical box. (Which, BTW, can't be removed because it ALSO is fastened to the supports in a manner that requires access to the wall interior) I that that could work, and might also try adding a magnet to the mix. But it will require another visit to the crawlspace, and I'm just not quite up for that kind of fun yet.

So I started work on problem #2: an ethernet run from the basement to the bedroom, which is a second-story location. I figure the total length of this run is still about 20 feet or so, not bad at all. But, not only are stapes involved, but this one is an outside wall. That means no crawlspace access, but also insulation to deal with. The main reason for this cable run is to enable the use of a VOIP phone.

I pondered the situation for a few days, then started checking out Ethernet cabling specs. It turns out that a 10Mb link requires only 4 conductors (2 pair). The not-quite-cat3 "mystery cable" (appears to be unshielded, untwisted) has 6 conductors. Phone associates at 10Mb anyway. Could it work???

YES! With some punch-down ends from cat5ecableguy, I've got it working. I still can't quite believe it, but it works.

Here are some links I found useful:

• Communication Wiring Color Codes


• RJ-45 pinouts


• CAT5 color code standards


• LAN wiring and pinouts (particularly interesting)

I recently wrote about Asterisk, the Free Software PBX. Well, I've completed the first stage of installation in our home and must say this is the most fun piece of technology I've played with since MythTV :-)

Here's what we now have in our home:

• Local calls can be dialed like usual. By default, they will use a landline (aka PSTN line). If the line is in use, they'll be routed over the Internet at a cost of 1.2 cents per minute.


• Long-distance calls can be dialed like usual. By default, they'll use an Internet VOIP provider at a cost of 1.2 cents per minute. If the Internet or the provider is down, they'll fall back to our landline, at the usual cost of 7 cents per minute.


• Toll-free calls can be dialed like usual, too. By default, they'll route over the Internet for free using FWD, but if that's down, they'll fall back to the landline.


• Almost every phone in the house will have its own unique extension number. These all start with "11" so they don't conflict with any public telephone number. So, no more running up or down two flights of stairs to ask a question.


• The IP phones in the house can also act as intercoms; when a special extension is dialed, they will ring once, then automatically go into speakerphone mode.


• We have call forwarding, 3-way calling, etc. without having to pay the usual high telco rates for these services.


• Call transfer is nice if one of us answers the phone, but the person wants to talk to the other person, who is in a different room. (And callers get to hear some nice music on hold while they're being transferred.)


• To a regular caller, it sounds like we have an answering machine if we don't answer. In reality, they are leaving a message on Asterisk's voicemail system. The system e-mails us the audio message as an attachment as soon as the person is done recording the message. Also, an indicator lights up on every digital phone in the house. We can check the voicemail from any phone, in our house or not, using a passcode -- or by listening to the attachment.


• By physically taking our IP phone to any broadband Ethernet port, we can make and receive calls on it almost like usual. Yes, if we take the phone to Indiana, and someone calls our Kanas number, phones in both Kansas and Indiana would ring.


• Emergency calls are routed over the landline like usual. In the future, I will set it up so that dialing 911 automatically disconnects anybody that's using the landline, so the emergency services can be contacted immediately.


• All analog phones are automatically connected to the normal landline in the event of a power or network failure.


• "Ring all phones" feature that essentially simulates an incoming call


• Caller ID everywhere, both for internal extensions and for calls coming in from outside


• All sorts of other fun stuff I haven't even tried yet...

Read on for a description of how it all works, and some hardware and vendor reviews...

At the center of it all is Asterisk. Asterisk is responsible for receiving and routing all calls, the fallback plans, etc. It's a very powerful and amazing piece of software.

Our digital phones are Sipura SPA-841 models. These are amazing phones, usually selling at $85. The Voxilla Store has the best deal with free shipping, plus excellent service. The SPA-841 comes with one Ethernet port and a modern-looking digital interface. It supports all the bells & whistles, such as 2 lines, call forwarding, call history, personal directories, speakerphones, distinctive ring tones, etc. It's also web-configurable, or can be configured via TFTP and XML files (very very nice if you have more than one!) The breadth of the configuration of these phon is just amazing.

Our analog telephone adapter (ATA) is a Sipura SPA-3000 (also with a good deal at Voxilla). This nifty little gadget sells for about $100 and has one ethernet port and two analog telephone ports. One of the analog phone ports is to be connected to the landline (PSTN) connection from your phone company. The other port provides line voltage, dialtone, ring voltage, etc. to phones in your house -- that is, it simulates the phone company to them. So, your analog phones can dial VOIP numbers -- and get the benefit of call routing over the Internet and the like -- all without having to invest in more-expensive digital phones. We are keeping our cordless analog phone (cordless IP phones are not very good yet), and a couple in infrequently-used by nice-to-have locations.

The PSTN connection lets you use VOIP to dial out. In our case, Asterisk is the one doing the dialing out, so the PSTN connection is controlled completely by Asterisk.

One super-nice feature of the SPA-3000 is that it has an option to bridge the two ports together in the event of power loss or if it loses contact with the Asterisk server. This is great so your analog phones keep working even in an emergency situation. Some people might disable this, though, because of the shock of having long distance suddenly cost 6 times more than usual :-)

The next stage in the project is to run some network cabling in the house so we can deploy an additional digital phone and relocate the server and ATA equipment to a more convenient location. Cat5ECableGuy has some great deals on jacks and cable. Service seems to be good, too; will let you know when my order arrives.

I also have a Sipura SPA-1001 (single-line ATA for use with analog phones) that I'll be deploying once the cabling has arrived. That will give the kitchen phone its own extension separate from all the others.

I have had a few hitches along the way. I first tried a cheapo Wildcat X100p clone from ebay. I found it to be unstable and cause asterisk crashes on my Alpha. The SPA-3000 is working much better.

The other hitch relates to disconnect supervision, which my telco doesn't provide. That means there's no good way for a machine to determine that the remote party has hung up the line. The SPA-3000 for some reason can't detect the off-hook warning tone either, but I have some workarounds going.

I also found that multiple simultaneous uploads on my DSL link would flood the transmit queue and cause latency to be unacceptably high for VOIP to work. After some tweaking with the Linux traffic shaper and ToS bits in Asterisk, I think I've got that nicely worked out.

I purchased some of my early equipment from Telephonyware. Decent prices, but they appear to have lied about the shipping date, and didn't return my e-mail asking about it. VOIPSupply had much faster shipping, but also really charges a lot for shipping & handling. Voxilla has good rates and fast service, so I'm using them now.

That's a lot for one post... more to come next week.

Since I wrote about Asterisk, the Free Software PBX, a few days ago, I've decided to start tinkering with it. In a word, Asterisk is awesome. It has lots of features, and is free, too.

Asterisk lets you manage your phones. You can set up extensions, letting phones call each other. You can also set up routes out -- connections to other offices, to the public telephone network (PSTN), or to other VOIP users. You can hook to the PSTN with either a $10 hardware device, or by using one of the many cheap VOIP providers, or whatever. And you can set up automatic call routing rules -- for instance, you might route local calls over your local PSTN link, but fall back to a VOIP provider if your local link is in use.

Here are some links for Asterisk information:

• The Asterisk wiki, an excellent resource


• VOIP phones, hardware phones that take an Ethernet cable, or software phonse that run on a PC


• VOIP service providers, listing some free IP-to-IP VOIP providers, as well as VOIP-to-PSTN and PSTN-to-VOIP companies.
  
  
  
  • FreeWorld Dialup is an excellent free VOIP-to-VOIP provider. They also have peering with many other VOIP networks; you can, for instance, call Vonage customers for free via FWD. FWD also has a free link to the PSTN for calling toll-free numbers in several countries.
  
  
  • VoipJet lets you call anywhere in the USA for 1.3 cents per minute, and LiveVOIP does the same for 1.2 cents per minute. With LiveVOIP, you can also purchase a phone number for incoming calls for $4 to $8 per month.
  
  
  • IPkall gives you a free local number in Washington state that forwards calls to your FWD account. There are some other companies that do similar things, too. Many also have very low rates on incoming toll-free calls.
  
  


• Asterisk tips and tricks is a great page


• Asterisk Handbook Project
  
• Asterisk Documentation Project
  

Two neat stories from Slashdot today:

First, an essay about fragmenting standards in the Linux world. I'm not certain yet if I think he's on the right track, but an interesting read nonetheless.

Then, and this is really cool, an article about building your own PBX using old hardware for under $20. Basically, this can give you things like voicemail, multiple phone lines in your house, etc. Fascinating read, and I'm probably going to have to try it out :-) They are using the Asterisk project.

Next, I decided I would periodically report on the, ahem, exacting quality standards of what we see in some of the mainstream news outlets.

Today, CNN leads with Martha Stewart saying "it's really wonderful to be back", a story about how Jackson needed a bathroom break at his trial, the White House denying it targeted the Italian hostage, and how Clinton gave up his bed on a plane to George H. W. Bush. Real news factor: low.

MSNBC fares little better with some Pope watching, "Jackson's private eye goes public" (whatever that means), the Jackson thing again (though sadly lacking in bathroom watching), and somebody surviving a drop from an overpass.

FOX leads off with "Boeing's new boss talks scandal!", a story on the "Jacko" defense, and after reading those two, I was too fed up to read any farther.

NPR leads off with "Syria vows pullback, large Hezbollah protests predicted", a story about the new U.N. envoy, the Italian reaction to the hostage shooting, and Sony's new CEO. Quite a bit farther down, I see a link to "'Bring Out Your Dead': Monty Python hits Broadway." Hmm.