eWorld: Building a Phone System: Part 1

Mar

Building a Phone System: Part 1

Published: Wednesday, March 07, 2007, at 08:42AM

Monday I started build-out on a new phone system for the office. I've never done this before, so I thought it might be cool to document the process here.

I got hired by Cartifact as a programmer, but it's not exactly my nature to stick just to that. I have a penchant for thinking I can do all sorts of things, so this fall I wrote up a proposal to replace our aging, cumbersome PBX with an Asterisk system and VoIP phones. The bosses gave the go-ahead, and now here I am building a phone system.

The Goal

At the office we have an NEC PBX that's been nothing but trouble since they had it installed. It's apparently impossible to find someone who knows the system to come and work on it; a couple times the company's paid people to come in only to have them sit there reading the manual. Configuration is done via a Windows app, but the program is a wrapper around key sequences that were made to be entered via the keypad, so it's anything but sensible in how it presents options. The result is that we've got a system that 90% works, but has never quite been all there.

The idea of a 100% software phone system really appeals to me. It says "anything you can think of is possible."

Building a Server

Asterisk is software, so it needs a host to run on. We didn't have a suitable box sitting around, so I built a server using a Supermicro SuperServer 5015M-MT+, a Xeon 3040 CPU, 2GB RAM, and a pair of 180GB SATA drives. The parts came in Monday, so I built up the box then.

I'm a Debian guy, but Debian Stable doesn't have the drivers for the Intel ethernet chipset on the Supermicro motherboard. I ended up going with Ubuntu server edition, which installed perfectly.

Monday afternoon I had a brand-new 1U rackmount up on the network with a fresh Linux install, waiting for action.

Connecting to the PSTN

The basics inside the office are very straight-forward: Asterisk server and VoIP phones. The real question is how you connect to the rest of the world. You can either buy interface hardware to connect to the PSTN right at the server, or you can trunk via IP to a provider who then interfaces you into the phone network.

The IP trunking solution was immediately more appealing, but for a while I wasn't confident I could come up with the bandwidth to support it. A big driver was cost: If I could get rid of the cost of our phone lines I could put that money into bandwidth and improve the general internet situation in the office.

Finally I found some great bandwidth via XO Communications, so in a few weeks we should be getting 5Mb ethernet service into the office. That allowed me to go ahead and decide on the IP trunking, thereby cutting out the extra hardware and lowering our upfront costs. I haven't chosen a provider yet, but I'll be getting into that more later.

Starting the Install

Yesterday I installed Asterisk and the GUI from Asterisk Now!, but just barely got to take a look at it before the day was over. I'll be doing some of that today, playing with interfacing soft phones with it.

Today I'll also be ordering a couple different handsets to check out before we make our final choice. Right now my leaders are the Polycom SoundPoint IP501 and the Linksys SPA942.

More soon as I get farther on this.

Comments

Ylee writes:

Good luck! Having done this before for my company, there are several holes. The biggest one I see is the VoIP termination ISP. How many simulteneous users do you need? My findings has been most VoIP ISP only provide services for 1 line and pricing for an office, of say 20+ users, are still costly. Most will give you an ATA for 2 numbers, but that does not scale for an office of 20+ for you will have all these ATAs strung up with no good way to mount them on the rack. Managing 10 of theses boxes is not something that you will want to take on as a part time phone guy at the office. My recent experience with XO was also not good. Albeit their pricing is cheap, so is their service. We had the PRI service turned up, and in a less than a week, it went down, in the middle of us configuring a new box that caused one of the guys thinking it was the config of the hardware. It turned out, XO made an error and ripped out our cross connect at the CO. Took them 2 days, 2 tickets (one was opened but never worked on). If this had been our primary line, we would have been hosed! The rep on the phone was not very helpful and only give 2 days of credit. So read your SLA! You will also need to frontend all you voice traffic with a voice VLAN, and that is yet another topic for another day.

# on Mar.08.2007 AT 07:47 AM

e; writes:

Our setup won't have any ATAs. It'll be a pure VoIP configuration, trunking over SIP/IAX to the provider. I've got some ideas of who I'm going to look at, but haven't yet chosen a provider.

We'll be on-net with XO, so no third-party loops are involved. Their data center is two doors down and I've already met several of their techs, so I think we should have some pretty good service.

I'll get into the VLAN stuff in a later installment as well. We've got a managed switch, so I can partition the network directly there.

# on Mar.12.2007 AT 03:43 PM

Nick writes:

well done...i am fasinated by this whole asterisk Solution...How on earth can i begin to build one..???

# on May.29.2007 AT 12:05 PM