John Goerzen: Asterisk At Work
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.
