Ditech Networks' Solutions
Codec Transcoding
Today’s telecommunications network is changing rapidly with the deployment of Voice-over-IP (VoIP) technologies. VoIP offers customers a tremendous increase in features and functionality, while enabling carriers to simplify network operations, reduce capital expenditure, and increase service revenues. With VoIP migration underway at most leading carriers, the network is continuously moving closer to ubiquitous end-to-end VoIP service.
During the transition to an all IP network, VoIP providers are routing voice calls through multiple networks, and calls must traverse multiple IP network borders. In addition to the need to support higher layer application-level peering for VoIP services, networks using IP peering are challenged with issues of media codec incompatibility, especially in larger cross-carrier networks. With an increasingly complex interconnection between networks, support for a flexible media and codec transcoding function is now essential.
| Supported Codecs | Ditech Platform | ||
*Future Capability |
Ditech’s Codec Transcoding feature is available on the Packet Voice Processor:
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The Need for VoIP Codec Transcoding
As VoIP becomes widely deployed, carriers must support different types of VoIP media streams that include uncompressed and compressed codecs, as well as various payload sizes. Early VoIP carriers chose to standardize their networks on a single voice codec (most notably G.711). While this approach allows a first step to deploying VoIP, it does not take advantage of the increased channel density, lower bandwidth, and enhanced voice quality made possible with different voice codecs. Supporting a single codec type also does not take into account the different bandwidth requirements that may exist with residential and enterprise VoIP services.
For example, in cable and DSL networks, it is common for the upstream link to be limited to a usable throughput of 128 kbps or less. If a VoIP provider is using G.711, the actual bandwidth utilized by a single channel is about 80 kbps when the complete set of IP headers is accounted for. With this limited upstream bandwidth, VoIP carriers are only able to provide and bill for one voice channel, thus minimizing the total revenue potential. This limitation could be alleviated with a compressed voice codec that utilizes less IP bandwidth (see G.729a and G.723.1 in Figure 1), provided that the compressed codec can be made compatible with the rest of the VoIP network.
Figure 1 – Channel Densities with Different Codecs
The Packet Voice Processor supports up to 13,440 channels in a single shelf and over 40,000 transcoding sessions per telco rack. Utilizing an advanced pooled DSP architecture, the Packet Voice Processor offers the ability to optimize bandwidth and serve the largest set of VoIP customers at an attractive cost per channel.
By deploying the Packet Voice Processor at the network border, providers can support a wide array of codecs from the customer premise or network edge and choose to normalize the incoming codec types before transmission to the IP backbone. This may also eliminate the need to perform transcoding at VoIP service points such as conferencing servers, media servers, and newer voice portal servers. This reduces costs and allows for easier deployment and the integration of additional enhanced VoIP service platforms in the future.
Service providers can also use the Packet Voice Processor to assign a particular codec treatment for specific calls based upon IP address, IP trunk group, or port using a defined service policy. With the Packet Voice Processor operating as a transcoding resource at the IP network border, providers avoid the expense of low-density solutions offered by border controllers, media servers, and media gateways.
Figure 2 – Packet Voice Processor Transcoding Feature
The Codec Transcoding Solution
Ditech’s Packet Voice Processor™ changes the rules for supporting multiple codecs. Built as a carrier-grade platform, the Packet Voice Processor offers providers the ability to significantly enhance service flexibility with support for the industry’s most comprehensive set of voice codecs for wireline and wireless applications. The Packet Voice Processor’s codec transcoding engine allows carriers incredible codec flexibility.
Conclusion
The Ditech Packet Voice Processor codec transcoding solution solves the problems of supporting diverse codec environments and enables increased service flexibility while enhancing VoIP service provider economics. Utilizing a scalable carrier-grade architecture, the Packet Voice Processor is a powerful voice processing resource that ensures flexibility with diverse voice codecs to expand service capability and maximize revenue.