By way of background, I have two phone numbers, one local and one toll free. The local number goes to an SBC phone line which comes into my home office and connects to a special card in a computer running the Asterisk@Home phone system. If the phone line is busy, SBC forwards the call to another number which is handled by VoicePulse Connect. Calls to the toll free number are also forwarded to the VoicePulse Connect phone number.

The Asterisk@Home phone system registers with VoicePulse Connect, essentially saying, “Here I am. Send calls to me.” Whenever a call comes into the VoicePulse number, VoicePulse transfers it over the internet to the Asterisk PBX. Regardless of whether a call comes in on the SBC phone line or via the internet, the Asterisk system answers it, presents a voice menu, handles voice mail, etc.

Arguably the most useful feature of the Asterisk PBX is that it routes the incoming calls to the phone on my desk. Asterisk accomplishes this by sending the call over the network in the office to a little box called a Sipura SPA-2000 phone adaptor which is plugged into the ethernet. My trusty old AT&T desk phone, which is plugged into the phone adaptor, rings and gently reminds me that my attention is required elsewhere than writing this article.

From a traveller’s perspective, magic can happen in the last step. Since Asterisk communicates with the phone adaptor via the network, there is no particular need for the phone adaptor and the PBX to be in the same building. In theory, you can take your phone adaptor anywhere in the world, plug it in, and your phone should work just like it does “at home.”

I decided to use a “soft phone,” rather than carry the phone adaptor and the telephone with me in my suitcase. The X-Lite softphone does everything phone adaptor + telephone combination does but it runs on my laptop computer. I picked up a lightweight Logitech headset, configured X-Lite, tried it in the office, and everything worked like a charm. Magic!

Being paranoid, I hauled my laptop and headset over to a friend’s office and tried the set-up. I was able to place and receive calls without a hitch.

With great confidence, I packed up my laptop on Sunday and took off in our plane for points east. Still unaware of looming trouble, I unpacked my laptop on Monday, plugged it into the network at the site I am visiting, hooked up the headset, and fired up Firefox to verify that I was on the net. Bingo! I could surf the web and even check my email.

I started X-Lite and watched with great anticipation as it… did nothing. Usually X-Lite comes right up and says, “I’m ready!” On Monday, though, it delayed for a minute or so and finally said, “Login timed out! Contact Network Admin.” Since I am the network admin, this was particularly depressing advice.

To make a long story slightly shorter, the problem ended up being the network configuration at the site I was visiting. Soft phones like X-Lite communicate with Asterisk using one of two protocols, either SIP or IAX2. For some reason, neither one would work from that site’s network. (I heartily thank Mark and Jim for going way above and beyond the call of duty in trying debug this and accomodate me.)

After spending a couple of hours trying every configuration trick I could think of with both Asterisk and the soft phone, I packed up, headed to my hotel, and tried again. To my great relief, everything worked perfectly on the first try. On Monday evening, I was able to use my laptop to place and receive calls through my office phone system.

My theory is that the problem was caused by the presence of both a NAT router and a firewall at the site. Architecturally, the non-functional configuration looked like this:

laptop -> NAT router -> firewall -> internet -> Asterisk

The problem was that both the NAT router and the firewall changed the apparent IP address of my laptop. Asterisk “knows” how to deal with one change of address, since both NAT routers and firewalls are common, but it cannot handle two changes of address.

Everything worked fine until Tuesday morning when I suddenly lost the ability to either place or receive calls. That second problem, it turned out, was caused by a long lasting power failure at home. Once power was restored and I got a neighbor to go and kick the recalcitrant Asterisk box, I was up and running and I am crossing my fingers that things continue to work.

Now that I have found a cooperative network (and XM Radio Online as well as my collection of MP3 files in iTunes), my travelling office is a delight and I am looking forward to more trips.

I feel like I have been conducting my own survey over the last couple of years. I started with Vonage, used it for a year, and then installed my own Asterisk@Home system to handle phone service for my home, my office, and my wife’s office.

Costs:

• Each incoming (DID) VoicePulse Connect phone number costs $11.00 per month.
• Outgoing calls via VoipJet cost $0.013 per minute to the continental US.
• The Sipura SPA-2100 telephone adaptors cost about $85 each and support two phones apiece. I have a pair of these, one for the office (my wife and I each have our own extensions) and one for the home.

To make Asterisk work, I have tried a bunch of VOIP providers. In a nutshell, here are my findings:

A note on “unlimited” calling plans. Many places want you to pay about $45 per month for an unlimited business line or about $20 per month for an unlimited home line. Those often do not make much sense. If you make your calls on VoipJet at 1.3 cents per minute, the break-even points are 3,461 minutes for a business line and 1,538 minutes for a home line. How much time do you really spend on the phone in a month? I talk a lot during the business day… and I am only on the phone about 2,000-2,500 minutes per month. And much of that time is on “incoming” calls which are free in any case.

Only Vonage supports emergency 911 dialing, though the FCC says that all of the VOIP providers have to start supporting E911 soon. I expect this will change. This is not an issue for me since I do have one real phone line coming into the house. If you pick up any phone and dial 911, Asterisk routes that call out on the SBC phone line.

All in all, this has been quite a trip. I have learned a tremendous amount, so it was worth it to me. I cut my phone bills by more than 50%. I increased my aggravation level by more than 100%. Would I recommend switching your home or SOHO to Asterisk and VOIP today? No, unless you like to play with techie projects. Would I recommend that you switch your home or SOHO to Vonage? Sure; without hesitation.

Asterisk@Home is a project to make Asterisk easy to install.

This is what I did:

1. Download the ISO image
2. Burn it to a CDROM
3. Boot from the CDROM
4. Let it do it’s thing (which includes repartitioning your hard drive, installing Linux, rebooting, installing and compiling Asterisk

It took an hour and I had a VOIP phone system making and receiving calls. Very easy.

I started out by getting VOIP DID for my home office and for Candy’s home office. Then I switched all outgoing calls to go out over VOIP, too.

On Tuesday, I ported our home phone number from Vonage, so now it comes in through AAH, too. It’s pretty cool to have all of the phone calls come through an old PC that used to be junk in the corner of the basement.

The Vonage service was nice, no complaints and highly recommended. But I couldn’t see paying for two all-y0u-can-eat VOIP phone plans. The big problem with Vonage was that I was required to use their phone adapter. I could not bring the Vonage traffic directly into my Asterisk box.

So here is what I ended up with:

• One copper POTS line for my office, connected to AAH. I kept this so that my local business number would stay in the phone book. I had SBC set this line up so that it “forwards on busy” to my VOIP local phone number. This, and DSL, are the only phone company services coming into my house.
• One VOIP DID for my office.
• One VOIP DID for Candy’s office. Since VOIP is completely virtual, we got her a Syracuse, NY phone number so that the main office for her company can call her without paying toll charges.
• One VOIP DID for our home. This number hasn’t changed in years. We successfully “ported” it from SBC to Vonage and now to our current VOIP carrier (who shall remain unnamed because I’m not very happy with them).
• My office toll free number is forwarded to my office VOIP number.
• Calling into my office gets a nice voice menu, whether you come in through the SBC line or the VOIP line.
• Calling into Candy’s office rings her phone directly.
• Calling our home number rings the home phones directly.
• If I don’t answer my phone, you get another voice menu which lets you choose between leaving a message or being forwarded to my cell phone.
• Candy’s office phone has voice mail.
• The home phone doesn’t have voice mail. We let the “real” answering machine handle that duty.

All in all, Asterisk is a pretty nerdy undertaking. I’ve learned a lot, not the least of which is that this is not “plug ‘n’ play” software.