Asterisk Termination and ENUM

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Asterisk Termination and ENUM

asteriskI discovered this interesting Asterisk termination post saved as "unpublished" dated 6-20-2005. I must have put it aside to work on some other projects. I thought I would publish it now since it still has some pertinent thoughts. Reading my article, I couldn't help but notice that it is two years later and there still isn't a sizable intra-enterprise VoIP peering network that I am aware of (with one exception - VPF). As I discuss in my thoughts from 2 years ago, I was hoping for a sort of P2P IP-PBX model where an IP-PBX from Company A communications with IP-PBX from Company B to initiate an outbound call at Company B's local calling rates. The other scenario is that you could simply initiate a call from Company A to an extension at Company B which travels over IP. In either scenario you can bypass ITSPs or the need for VoIP gateways entirely. One option is for Company A to "peer" directly with Company B, by contacting them and configuring some call routing settings. However, Company A would have to contact several companies to peer with before realizing any cost savings.

The other option as I mention below, you would require some sort of trusted third-party to act as a go-between and to centrally organize all the various peers to reach the critical mass needed for real phone cost savings. ENUM is supposed to help with that, but the carriers aren't exactly rushing to offer ENUM and certainly not "free" ENUM services.. One interesting ENUM registry is from the Voice Peering Fabric (VPF). The ENUM registry is based on the IETF (RFC 3761) standard which maps telephone numbers to Internet (URL) addresses and uses a look-up architecture based on DNS They built their own ENUM registry, which is a multilateral peering service that allows organizations to send and receive calls among members directly, IP end-to-end, for no termination fee, including no cost to register numbers or querying the registry. It's free. Let me repeat that - it's FREE! Querying the ENUM registry is free and so is terminating a call to another VPF customer. Thus, as the VPF adds more corporations to their customer list, this also increases the number of FREE calls you can make. Kudos to the VPF which isn't waiting around for public ENUM to finally take off. I expounded the benefits of ENUM in my "ENUM ENUM ENUM!" post, which is a good refresher on ENUM and I compare public ENUM registries versus private ENUM registries.

Ok, without further adieu here's the post I started 2 years ago. Enjoy...

Asterisk has had the ability to call other Asterisk PBXs for terminating calls over an IP connection for quite some time. Thus, if you have multiple branch offices all with Asterisk PBXs, you can terminate calls over the IP connection for free.

Hunter Newby over at Telx and I discussed how it would be very easy for Asterisk PBX users to join in a massive Asterisk community and "share" their connection and barter/exchange minutes. Let's call it "enterprise peering". It's actually a form of "peer-to-peer enterprise telephony" actually. In theory, you can get a "cut" of the revenue for the PSTN minutes that call out of your Asterisk PBX. This is a scary concept since eventually all enterprises can "peer" with other enterprises and essentially negate the need for the PSTN altogether - another nightmare for the phone companies caused by VoIP.

There are two scenarios when peering between two corporate IP-PBXs. The first scenario is where an IP-PBX from Company A communications with IP-PBX from Company B to initiate an outbound PSTN call at Company B's local calling rates. Company B charges Company A for terminating the call. The second scenario is that you could simply initiate a call from Company A to an extension at Company B which travels over IP. Since it's all over IP, the call is free.

Of course, the Asterisk system uses its proprietary IAX protocol for inter-Asterisk communication and not standard SIP, so unless IAX is supported by all IP-PBXs (not going to happen), this particular "doomsday scenario" for the phone companies may just be a dream. It also requires that each Asterisk IP-PBX trust other Asterisk IP-PBXs to not abuse or max out their limited outbound PSTN resources.

Just imagine if the SIP protocol matures to the point where you can securely "peer" with other SIP-based IP-PBXs and some sort of clearinghouse takes care of bartering minutes, revenue exchange, etc. Of course, you could bypass a clearinghouse altogether and just let outside SIP IP-PBXs dial out over IP through your PSTN connection free of charge, but there would have to be some level of "trust" to allow this to prevent abuse.

In theory, you could charge outside IP-PBXs only after a certain usage criteria has been met, but that opens the door to fraudulent billing practices. Company A could say that Company B owes it $500 for making SIP calls over its PSTN lines. That's why an independent third-party clearinghouse would be needed to prevent billing fraud. In theory, with a large enough "trusted" clearinghouse you can join this clearinghouse network and it would provide the least cost routing and calculate what revenue you are owed by those that terminate calls on your PSTN lines. Essentially, using your corporate IP-PBX you become your own little phone company making your corporate IP-PBX a revenue source instead of a liability.

In a very similar fashion to this idea, it appears one company called AsteriskOut is using multiple Asterisk PBXs for termination. I was perusing the VoIP Forums and came across this Asterisk thread in the VoIP Forums where a company is leveraging Asterisk to terminate VoIP calls, but it doesn't appear they are building any sort of peering model. AsteriskOut has some decent rates, including just $0.016 per minute for U.S. termination.

Is enterprise-to-enterprise IP-PBX peering just a dream? With the help of a large enough and "free" ENUM database it is certainly possible. Or perhaps with Asterisk's continued growth, the open source community will create a popular Asterisk ENUM (AENUM?) registry of their own which will reach critical mass and even cause other IP-PBXs to join. Only time will tell.

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