My break with traditional telephony

by Matthew Gast

I was recently traveling in Hong Kong, and I had to repeatedly work around the hotel telephone service. There was a $6 fee to connect an international call, which cost almost $1/minute after that. The alternative was my mobile phone, which was able to roam on to networks in Hong Kong at the cost of $1.49/minute. At one point during my stay, I participated in a conference call by making a short call to the United States so that one of the other participants could call me in my hotel room halfway across the world.

Enough is enough. At the end of that trip, I decided to sign up with voice over IP service. By finding a provider that would support my travels, I could cut down on international telephone bills dramatically. As I searched out a provider, I looked for two main features. One was the ability to take the phone anywhere and have it work, and the other was a provider that would allow me to use a soft phone. Eventually, I settled on BroadVoice because they will give you SIP credentials, which means that you can use any device or software you want. BroadVoice also offers a "bring your own device" option that saves on the activation fee. By purchasing a device ahead of time, I could offset the cost with the savings on the activation fee. I decided on a Sipura SPA-2100, since it has a built-in router. In hotels that lock down Internet access to a single MAC address, I'll be able to use both VoIP and generic IP data.

Setup of the service was easy, once I worked through problems with my own network. (My DHCP server quit assigning addresses, which took me for a while to find.) BroadVoice supplied directions that walked through resetting the device to defaults and pointing it to BroadVoice's gateway. It downloaded upgraded software, connected up through NAT without a hitch, and started making calls. If I take out all the problems I had with my own network, it took about ten minutes to get running.

Once I had calls flowing, I had to prioritize them. VoIP is time sensitive, unlike uploading huge multi-megabyte presentations. I can prioritize upstream traffic at the edge of my network, but I have no control over downstream traffic. For now, I have to hope that I have enough capacity in the downstream direction to provide good voice quality. (This is one of the major selling points to getting VoIP from your Internet provider. In theory, they can prioritize the downstream direction, too.) Prioritization required three major steps:

  • A static IP address in the DHCP server for the telephone adapter. I want the telephone adapter to use DHCP so it can migrate from network to network, but I need a constant address on my network to prioritize traffic from.

  • New service definitions: UDP ports 5,060 to 5,063 for the Session Initiation Protocol (SIP); UDP ports 10,000 to 20,000 as the high-numbered ports to carry the call data; and a group that lumps both together as "VoIP".

  • A new firewall rule that prioritizes traffic using the "VoIP" umbrella service from the address of the telephone adapter. Call quality suffered at a 64 Kbps reservation, so I bumped it up slightly. (BroadVoice also wants UDP 69, TFTP, allowed. I assume this is for software upgrades, so I didn't prioritize it.)

Prioritization appears to be working quite nicely. I experimented on family & friends over the weekend, and I'm told that the quality of my voice when I run a line-saturating speed test is better than many conversations I've had with them from my mobile phone.

In an amusing postscript to the story, the local phone company sent an insert in my bill which claims that our telecommunications laws are outdated and need to be modernized because the local phone companies want to bring me the future faster. I couldn't help but borrow a phrase from William Gibson: The future is here. It's just not being distributed by the telephone companies yet.

How do you prioritize VoIP on your home network?


2005-02-07 16:43:29
My experience with Voicepulse and Packet8 has been much the same--most people can't tell the difference between a VoIP call and the old landline. And you're right about the phone companies. They're very good at maintaining the network and very poor at creating compelling services that empower the user.
2005-02-08 12:06:24
Death to traditional telephony indeed...
I've recently started using Vonage and love it. In fact recently blogged about my initial experience using the service for the interested.

Read the blog entry

Jason G