Tom Keating : VoIP & Gadgets Blog
Tom Keating
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Slowly but surely, the VoIP industry is beginning to embrace ENUM, a standard protocol for resolving phone numbers into IP addresses. ENUM was originally developed to link consumers' phone numbers to various IP services, as well as allow for multiple VoIP devices to be called using a single number. However, the ENUM standard is proving even more important in interconnecting carriers' VoIP networks.

ENUM lets carriers interconnect VoIP networks directly and avoid access fees for transmitting calls over the public switched telephone network (PSTN). Let me give you an example. Suppose a user of Vonage tried to call an AT&T CallVantage customer. Unfortunately, the call must hop off the IP network onto the PSTN and dial the PSTN number of the AT&T CallVantage customer - IP-to-PSTN instead of IP-to-IP, real efficient right? Also, Vonage pays more money any time it has to use the PSTN to complete the call as well as use one of their Vonage's valuable port resources.

So anytime Vonage or any broadband VoIP service provider can stay on the IP world and not touch the PSTN, that's a very good thing. Now suppose AT&T puts its CallVantage customers' phone numbers in an ENUM registry. Tthe call from Vonage can query the ENUM registry, find the target phone number listed, and connect directly to AT&T's VoIP network (and the customer) without ever crossing the PSTN! So it's an IP-to-IP call... ahhhhh. much more efficient...

Even cable companies realize the benefit of keeping calls on IP networks even if that means terminating a call on a competing cable companies IP network. Also, consider that carriers are probably the #1 enemy to the cable companies (well, satellite is up there too). So if cable companies are the enemy of other cable companies and surely the carriers are the enemy of cable companies, does that mean "the enemy (carriers) of my enemy (cable companies) is my friend?" Indeed it is. While cable companies do compete somewhat with each other, cable companies are very much bound be geographics. In my neighborhood, I had one choice for cable - Charter Communications. So the cable companies fight each other much less over customers than the carriers fight each other over acquiring and retaining customers. So in my opinion, cable companies are much more amicable towards each other. There is also a spirit of unity of "Let's work together to beat the carriers" mentality going on in the cable company sector.

ENUM would help cable companies avoid paying reciprocal compensation to local exchange carriers. Under Federal Communications Commission (FCC) rules, service providers must pay reciprocal compensation when calls pass through a carrier's network and then terminate at an Internet service provider. For example, AT&T pays $8 billion a year in reciprocal compensation to local exchange carriers for terminating calls.

No wonder AT&T abandoned the residential long-distance market! (that was tongue in cheek.) Actually AT&T has NOT abandoned the residential market, but they sure fooled a lot of industry analysts and journalists who took AT&T's "bait and switch tactic" and posted news articles claiming AT&T had surrendered the residential long-distance market. I blogged AT&T's true intentions - that they were going around the "back door" and using VoIP to target the residential market, thus bypassing the FCC rules about reciprocal compensation and saving $8 billion per year and more due to the cost efficiencies of VoIP. (You can read those three blog entries related to AT&T's residential focus here and here and here - it was important enough to blog it THREE times.)

One such company trying to offer ENUM services to the cable companies is NeuStar. "There's a huge business driver here," says Richard Shockey, senior manager for strategic tech initiatives at NeuStar. "The MSOs have a strong economic interest in maintaining VoIP calls end-to-end on IP. ENUM is the most efficient signaling technology available to achieve that goal."

Of course, one problem is how do we get a single universal ENUM registry database so we don't have fragmentation with tiny little ENUM islands all over the world. The owner of that registry certainly stands to make money. Just look at VeriSign or GoDaddy, both of which have made millions of dollars from their Domain Name System (DNS) registration business.

Essentially, there will be a Public ENUM and a Private ENUM. According to Verisign's ENUM FAQ, the key differentiator is the DNS root, which for Public ENUM will be e164.arpa. Public ENUM will be openly accessible, thus there are some concerns about privacy, authentication and security. Private ENUM will not use the the e164.arpa root, and the data will not be publicly accessible. Private implementations will be designed for specific service provider solutions. Public ENUM plans to date have been for a Global Public Directory Service, managed by Country Code and NPA. Both the circuit switched telephony and DNS infrastructures will be utilized. Anyone who wishes to have their contact information available through this Directory will need to "opt-in" for the service. Industry infrastructure for the U.S. and other sovereign nations under Country Code 1 is pending definition. This definition is being driven by a group that is attempting to create an ENUM LLC, with some input from the NTIA, FCC and State Dept.

VeriSign in fact has been moving towards offering a similar service in the VoIP realm with a series of announcements this year. I discussed one such important announcement on October 11th, 2004, which was titled Verisign and VoIP using SS7 and SIP. Verisign also introduced MSO-IP Connect, a service that uses the ENUM and Call Management Server Signaling (CMSS) protocols to route VoIP calls between cable operators and other VoIP carriers through a secure system. According to their website, "VeriSign's MSO IP Connect service bridges disparate cable VoIP networks and legacy systems to centralize voice and data management, reduce costs, and allow MSOs (Multiple Systems Operators) to offer an expanded selection of value-added services. With MSO IP Connect, cable providers can service their customers by establishing a single connection point to the VeriSign network, rather than maintaining multiple interconnection points. With access to more end points via the VeriSign network, MSOs can extend their VoIP reach, and begin to eliminate PSTN interconnection costs."

Take a minute to soak that up... In fact, go back and re-read it - it's that important. If you don't see the handwriting on the wall that the traditional PSTN is dead, well I can't spell it out for you any more clearly.

"There are islands of VoIP," says Tom Kershaw, VP of next-generation networks at VeriSign. "And those islands need a trusted third party to connect with each other. When you default back to the PSTN, a lot of the features of VoIP don't work, like you can't do video or collaborative workflow. So, having an end-to-end VoIP connection is critical to enabling the service suite."

Verisign isn't the only one jumping on the ENUM bandwagon. Stealth Communications Inc., a New York-based ISP, added an ENUM registry to its Voice Peering Fabric (VPF), an exchange that lets VoIP carriers buy and sell minutes. VoIP carriers can not only route calls over each other's networks, but also look up numbers on each other's networks to interconnect calls and negotiate access rights. "There are about 1.2 million numbers in our ENUM registry," says Shrihari Pandit, CEO of Stealth Communications, which charges a monthly fee for use of the VPF.

"ENUM changes everything" said Shrihari Pandit, CEO and Founder of Stealth, "ENUM is a network protocol that takes a telephone number and resolves it to a URL, like the way a traditional Domain Name Server (DNS) takes a URL (like www.google.com) and converts it into a numeric IP address. With ENUM, the telephone number is sent to the DNS server, which then replies back with a list of URLs. This opens up a whole new world of applications and services driven solely by a phone number," says Pandit. Stealth's VPF ENUM Registry presently holds over 1.2 million phone numbers. While this represents only a small number of the total phone numbers in the US, Pandit is quick to point out that "ENUM represents truly disruptive technology, in that it has the potential to obsolete the public phone network." Pandit envisions a day when Stealth's VPF ENUM Registry will house most, if not all of the phone numbers on the planet.

Unfortunately, some carriers are opting to run their own private ENUM registries and getting users to register on a "public ENUM" registry has been a hard sell - what's their incentive to do so? Hopefully, ENUM will not become fragmented. But perhaps like DNS, no one will truly "own" the ENUM registry, and just like DNS, which replicates new DNS entries to DNS servers across the world, hopefully as more private ENUM registries spring up, they too will "replicate" to other ENUM registries and not keep the registations "private" and unshared. For now, I do foresee private carrier-based ENUM registries outpacing any sort of open, public ENUM registry, but I also foresee these registries "communicating" and sharing registration information with each other in the near future. The cost saving and benefits are just too great to ignore. ENUM will reach a critical mass in 2005, with VoIP providers exchanging minutes and VoIP customers able to reach other VoIP customers in other VoIP networks without touching the PSTN -- you can bank on it. That's my one prediction for 2005.

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