ISN/Freenum and why you should care.

I wanted to take a moment and discuss a cool telephony technology that I think everyone should be aware of. Why? It's going to change the world.

From the freenum.org website:
"The Freenum/ISN system is 12-digit-keypad (telephone handset) friendly method of providing mapping between users. While the eventual use of email-style URI pointers is the eventual goal for communications identifiers, it is still the case that the majority of the world's telephony users are trapped using a 12-digit keypad for extended numeric entry, and it is for the purposes of these devices that the Freenum system and ISN dialing was designed as a "stopgap" which may last many years. Using ENUM-like methods and IETF standards but not using telephone numbers, the Freenum/ISN dialing system is designed to initially allow SIP-capable proxies and iPBX systems to connect to each other in a free, open, and protocol agnostic manner over the Internet. Initially focused on SIP voice communications, the platform is hoped to eventually extend to other communications methods as those protocols become more widespread."

What does this mean in plain, simple English? It means that using this technology any person in the world can communicate to any other person in the world for no more than the cost of the bandwidth of the call and a little tech savvy. There are plenty of free VoIP clients (X-Lite, SJPhone, Zoiper just to name a few.) If you have asterisk or know someone who does (or any sip proxy, for that matter) you can likely piggyback on their system for ISN resolution.

Let me explain a bit about how this works such that a layperson might understand. Lets say I have relatives in, I dunno, Cambodia (Or insert random country here.) They have high speed internet access and so do I. How do I call them cheaply? Sure, I could use something like vonage and pay per-minute rates. But why bother? We can use the internet from one side of the call to the other, with no issues.

Now, a lot of people might be saying "But you can just use the remote computer's IP address and put that in the client to connect!" Yes, of course you can. The thing that makes ISN pretty cool, however, is that instead of remembering an ip address or a hostname, you only have to remember a relatively small number that is similar to a phone number. In my case, 230*739 will get my desk at home. In the previous case, you would have to type a line similar to sip:ip1-5-7-2-blah.core1.cambodia.has.long.dns.entries.kh or something. Even if you used their dynamic dns service (that you had to teach them how to use) it'd still be sip:petescambodianfamily.dyndns.org. Wouldn't you rather dial something like 1234*800?

The easiest method to use isn is to get on a free SIP provider such as Free World Dialup. They already have ISN built into their sip proxies and all you had to do was download a sip client and sign up for the free service. Now, granted, you could have both you and your cambodian buddies get free world dialup and never even have to use ISN. But, then you'd be missing out on learning about a new technology in the process that might just make your life easier!

ISN is designed to utilize DNS for it's resolution. When you dial 1234*800, what's really happening on the proxy you are connected to is, they're doing what's called an ENUM lookup to 4.3.2.1.800.freenum.org. This lookup produces (via a NAPTR dns entry) a URI that can be used to call. For example:

pgrace@fmservices:~$ host -t NAPTR 0.3.2.739.freenum.org
0.3.2.739.freenum.org NAPTR 100 10 "u" "E2U+sip" "!^\\+*([^\\*]*)!sip:\\peter.grace@hermes.fierymoon.com!" .

This record in simplified English just tells the sip proxy that it needs to call sip:peter.grace@hermes.fierymoon.com whenever someone dials 230*739 via ISN. The best part is, most people will never need to know how this works. It will "Just Work", thanks to you, the techie of the household.

There are plenty of people on the internet and in the isn community that will be happy to help you setup ISN if you already have a working sip proxy. There are also many people who will help you setup an asterisk box if you have a bit of linux skills and are willing to learn the nuances of voip.

It gets better though.

Lets say you have kids in college. You want to be able to call them from home cheaply, and they want to hit you up for cash regularly. Who wants to pay money for these calls? It's like you're really paying them 102.50$ for every 100$ you put in their bank account.

Luckily for you, a lot of universities have already signed up for ISN. They will be rolling out their extensions via ISN to link into their campus phone networks soon if they have not already done so. What that means is, your child who has an extension in their dorm room of say, 2325, all you'll have to do is dial 2325*<itad>. Lets say your kid goes to Wayne State University in Detroit (Random college I pulled from the ITAD List). Their ITAD is 533. By dialing 2325*533, voila, you have just connected to your irate daughter as she was about to go clubbing with her roomies, and the best part is, you're not paying for the call!

Little Jenny needs some more money? If you signed up for Free World Dialup or any of the other myriad sip providers that support ISN, all she'd need to do is dial <your fwd number>*262 and voila, her nice little neon lightup phone from the 80's has made a voip call to your PC.

There is a caveat to this, and that is that ISN is still considered early-adopters territory. Not everyone listed in the ITAD list has a legitimate termination setup for ISN. Some places have flakey sip proxies. This is definitely more bleeding-edge digital convergence stuff than some people are used to dealing with.

That being said, my asterisk box is always up, go on ahead and give me a call at 230*739!