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October 2008 | Volume 11 / Number 10
The Channel Perspective

Morphing VoIP Providers OR VoIP Providers Needs are Changing over Time

Providers need an inexpensive solution for hosting multi-tenant, secure, scalable VoIP services. Such a solution is now available in the marketplace.

Traditional Provider

When VoIP technology first moved into the mainstream, solutions were rare and expensive. Solutions introduced included Session Border Controllers (SBCs), softswitches, and Gateways. Softswitches started replacing the hardware switches from manufacturers like Nortel. Companies like Broadvox (News - Alert) and Metaswitch provide the softswitch technology at a high cost. For a provider to get started, it was common to spend $250,000 to millions, not including the personnel expense that was needed to support the equipment.

VoIP has a variety of problems on the Internet. For example SIP was developed without regard to NAT and doesn’t work well when a VoIP phone is behind NAT. Manufacturers developed devices like Session Border Controllers to support VoIP. These include Acme Packet (News - Alert), Kagoor Networks, Jasomi, Netrake, and Nextone. These devices helped backbone providers, and VoIP service providers to ensure the quality of each call. They are expensive and complex.

New Age Provider

With the introduction of Asterisk (News - Alert), resellers started delivering dedicated iPBXs to small and medium enterprises. Many entrepreneurs were targeting the same market based on the same technology, a copy of Asterisk running on a server.

Systems for Providers

There is a different market for service providers. Service providers want to provide services for multiple customers, not just give a single customer a single dedicated PBX (News - Alert). It’s hard to do this with Asterisk. Asterisk doesn’t scale well, it’s not an easy multi-tenant solution. Trying to support more than one company’s iPBX with Asterisk requires adding a SIP proxy like SER or Open SER and a lot of custom scripting and coding. It turns out that Asterisk, while good for the individual company, does not work well as a multi-tenant solution, even when combined with a SIP proxy like SER.

The next attempt to improve the ROI was virtualization. Asterisk doesn’t work well with either ZEN or VMWare. They both are limited to running a few copies of asterisk on a single Server. They have serious problems withe the real time clock and timing for Asterisk. Conferencing and voicemail don’t work correctly.

Asterisk as a provider solution has scaling issues. Each instance of Asterisk will only support about 900 SIP phones. This is a major limiting problem for the VoIP provider. Transcoding is a serious issue. For example a server may support 400 to 450 simultaneous calls without transcoding. Transcoding G.711 to G.729 will limit the server to about 125 calls. If it is G.711 to ILBC, the server can support about 15 calls.

Solutions of the Future

Asterisk has been the de facto standard for the VoIP open source community. This may be the result of its having been designed as an iPBX. The limitations identified above caused many early users to reconsider the use of Asterisk. Some, such as Panterra Networks, would develop proprietary solutions that have been in production for years.

Others decided to design another open source technology from the ground up to be used as a softswitch by VoIP providers. Those visionaries started the FreeSWITCH movement. The product was designed for more than a year before coding started. FreeSWITCH has been gaining momentum and has a substantial following. Most want a softswitch that is superior to any Asterisk-based softswitch. FreeSWITCH is about to release 1.0.2.

Ring Carrier provides a multi-tenant scaleable that uses Asterisk as a component. Ring Carrier runs from 50 to 75 copies of Asterisk on a single server. This fixes the multi-tenant issue because it’s cheap and easy to give each tenant their own Asterisk PBX. It’s easy to scale. Ring Carrier provides a gateway for the colo that scales from 4-T1s to 64-T1s or 1-DS3 to 3-DS3s or 1 OC3. The gateway performs the transcoding. A single gateway transcodes up to 2,048 channels simultaneously from any CODEC to any other CODEC. Up to 16 of these units can be linked together. Ring Carrier is just now bringing to market a new gateway for the customer premises that provides for QoS and security and fixes NAT and other problems.

Don Witt is President of Cylogistics (

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