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September 1999

Gatekeepers Hold The Keys For Carrier-Grade IP Telephony


Internet telephony is the ideal technology for carriers wanting to balance customer demands for low-cost, enhanced telephone services with their own needs for profitability. But there’s only one hitch: There are few DS-3 level IP switches currently available in the market that can support carrier-grade IP telephony. While some enterprise-sized Internet telephony switches can be stacked to meet increasing call volume needs, they still can’t come close to carrier-grade call volumes — the enterprise switch typically has a capacity of about one million calls per month, while carrier-grade switches need to handle at least 300 times that call volume. Furthermore, carrier-grade IP telephony services also need far more reliability, scalability, global expandability, and interoperability than enterprise-scale switches.

Interestingly, the obstacle many carriers are facing in their attempts to implement IP telephony is not converting large numbers of voice calls to IP packets and then back to voice again — voice-over-IP (VoIP) gateways have solved that problem. Rather, the difficulty in achieving carrier-grade service lies in developing a gatekeeper capable of simultaneously tracking millions of calls on numerous gateways in a global network, authorizing all calls in real time, and then rating and routing them. To repeat: The key to a successful carrier-grade IP telephony network is not the gateway, but rather the gatekeeper.

In addition to having a scalable operating system, a gatekeeper must also be able to communicate with other gatekeepers in the network at the lowest possible level. This is critical in order to achieve full mirroring among gatekeepers, and thereby duplicate the processing of all calls — an essential element in providing the reliability required for carrier-grade IP telephony. With full mirroring across multiple gatekeepers, and no single point of failure, should one device fail, network operations can proceed unimpeded, with no calls being dropped and no impact on callers.

Tight integration among gatekeepers is also a key factor in achieving a scalable solution. As call volumes and geographic presence increase across a carrier-grade IP telephony network, additional gatekeepers will be required, and all must be seamlessly integrated with the existing infrastructure. Without this easy integration, network expansion costs will be unnecessarily high, and problems could occur when handling calls across disparate equipment.

Another critical scalability issue in achieving carrier-grade IP telephony is database latency. At the core of any gatekeeper is a relational database that stores all authorization, rating, and routing data. All gatekeeper applications query this database when processing calls, and, as the number of callers increases, so too can the time it takes for the database to process queries. But, in a carrier-grade platform, even a small delay is unacceptable, so gatekeeper developers must come up with ways of eliminating this latency issue. Various database processes, such as reporting, database updating, or caller authorization, may be divided across multiple copies of the database, for example, or queries may be carefully structured to be as “lean” as possible. The bottom line: In order for a gatekeeper to support carrier-grade IP telephony, it must be architected with the intelligence to optimize utilization of a relational database and eliminate latency.

Globalization is another scalability issue that carriers need to confront when establishing an IP telephony network. Not only must the homologation requirements of each country be met, but operational interfaces must be multilingual, and billing systems need to be multi-currency. In addition, the overall network should be constructed with a peer-to-peer flat architecture in order to ensure that gatekeepers throughout the network can communicate with one another and route international traffic appropriately, addressing varying load conditions in various countries, at various times.

In a global network, interoperability is another critical concern for a carrier-grade IP telephony service. To achieve interoperability, calls must be able to be transferred across multiple networks and get translated back into analog voice in the receiving network that delivers the call. But the challenges of interoperability by no means end here. Far more complex is the issue of interoperability among gatekeepers for the entire call handling process — including authorization, rating, routing, and billing.

In other words, global requirements mandate that it is not sufficient if a given carrier’s gatekeepers are all integrated and interoperable. Equally important is the ability of the gatekeepers of one carrier to communicate with those from a competing carrier, possibly in another country.

Presently, the difficulty in achieving gatekeeper interoperability is the fact that the emphasis of standards setting bodies has been on the actual voice and video content of the call (e.g., H.323); no standards yet exist for gatekeeper interoperability. However, this current shortcoming does not imply that carrier-grade, international IP telephony is not ready for prime time. By implementing a gatekeeper that is modularly architected for flexibility, carriers — and their customers — can immediately gain the benefits of IP telephony, while also providing a pathway for supporting evolving standards. As a result, when standards finally do get released, investments will be protected, even while the IP telephony network becomes interoperable with its global peers.

The benefit of acting now, rather than waiting for standards to evolve, is evident: The sooner IP telephony is implemented, the sooner the benefits will start accruing. And, while some industry pundits may say that the urgency for this technology is fading as the prices of conventional telephony fall, this is not the case.

True, call costs may not be the driving factor they once were. But carrier-grade IP telephony can provide more benefits than just calling cost. Enhanced services may be implemented in conventional telephony networks, but implementing them in IP telephony platforms is far simpler, significantly less expensive, and much easier to manage. In addition, a wide range of features that are just not possible with analog telephony can be easily implemented on IP telephony platforms.

With IP telephony, any application that needs a computer back-end — including video conferencing, address books, point-and-click conferencing, and integrated unified messaging — can be implemented as a network service, and be easily propagated throughout the network. In analog networks, multiple duplicate hardware platforms may be required throughout the network, a situation that can create a sizable management headache. Furthermore, only IP telephony offers a future rich with new services. Constant online voice communication among a defined community of users, for example, is an application that just would not be possible with conventional telephony.

What it comes down to is that with a robust, carrier-grade IP telephony network, enhanced services will not be limited by the technology, as they are with analog telephony, but only by the creativity of the service developer. For carriers seeking to differentiate their services and carve out a strong competitive position in increasingly crowded markets, this is exactly what they need to successfully meet their business objectives. 

David Greenblatt is Chief Operating Officer of the Net2Phone division of IDT. He has helped make the Net2Phone service and its technology a well-known brand in the exciting and exploding world of Internet telephony. Net2Phone routes millions of Internet phone calls and faxes each month. He welcomes your feedback at [email protected]

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