IP-to-IP Transcoding for Carriers - Market Requirements

The IP world is not homogenous. Session Border Controllers are focused on call signaling adaptations while the need for adaptations on the media layer is heightened. IP-to-IP Media adaptation is primarily related to transcoding from one vocoder to another, however there are some additional media manipulations that might be required: voice quality enhancement capabilities such as gain control, and security related enhancements such as RTP to SRTP.

The drivers for IP-to-IP transcoding are diverse:

• Carriers who mandate a homogeneous codec environment for simplification and interoperability reasons
• End terminals with no common vocoder
• Vocoder licensing costs
• G.711 optimized install base
• Bandwidth constrained links (i.e. satellites, cellular)
• Gain issues
• Wideband vocoders
• Cellular to wireline calls

Generally speaking, the rise of IMS core networks leads to additional transcoding requirements as these networks seek to connect to multiple access networks, where each one may use a variety of media formats.
 

IP-to-IP Transcoding for Carriers - AudioCodes Solution

AudioCodes’ transcoding solutions are based on its Mediant VoIP Media Gateway product line. The IP-to-IP transcoding capabilities enhance the Mediant TDM-to-IP capabilities.

AudioCodes is a leading provider of voice codec technology, and is internationally recognized for its DSP and codec development. AudioCodes’ voice codecs have received outstanding scores by third party auditors and offer one of the highest densities per DSP.

The Mediant additionally showcases one of the most extensive set of vocoders available on media gateways. This includes a new breed of wideband vocoders such as WB-AMR and G.729.1.

AudioCodes High Definition VoIP initiative seeks to change the voice quality people are used to having on their private and business calls, by supporting the infrastructure required for end-to-end high definition calls. AudioCodes transcoding solution is capable of performing  High Definition transcoding from one wideband vocoder to another, without going through low resolution PCM. This functionality is necessary, in a world where multiple wideband vocoders exist, for achieving a true end-to-end High Definition VoIP experience.
 

AudioCodes transcoding solutions fit any type of architecture:

• Managed transcoding solution: can perform IMS MRFP and IMS IBGF functionalities using the H.248 control protocol
• Stand-alone transcoding solution: Mediant performs SIP B2BUA and transocodes any call which requires transcoding and then passes it over to the  SBC or SIP proxy

A service provider may also choose between a single centralized transcoding element or a distributed approach where a Mediant gateway is placed next to each SBC or SIP proxy at the borders of the service provider’s network extending the SBC with transcoding capabilities.
 

IP-to-IP Transcoding for Carriers - Features

• Wide range of simultaneous coder options including: G.711, EG.711, G.723.1, G.729a, G.729.1, GSM EFR, GSM FR, AMR, WB-AMR, EVRC, iLBC, G.722
• Low-latency and low-jitter
• Managed solution using H.248
• Stand-alone solution using SIP B2BUA
• TDM to IP
• Voice Enhancements: Gain Control, Silence Supression
• Security: RTP to SRTP
• SIP normalization (for example SIP/TLS to SIP/UDP)