VoCeM - Voice Compression and Enhanced Multiplexing

Vocem works by increasing Inmarsat or Ku-band payload usage by a factor of between four and ten. Not only is the kbit rate for each call reduced, but also the number of simultaneous calls is increased.

Currently, VoIP calls use up to 96 kbit/s, GSM use up to 30 kbit/s; using Vocem, each call will only use 6 kbit/s. And up to 120 simultaneous calls are available.

Vocem can also be added to any existing GSM, 3G/UMTS or VoIP satellite communications system, provided by any supplier, with a simple software upgrade.

Vocem technology is integrated into all TriaGnoSys products. It can be used for all forms of remote communications systems, including passenger and crew GSM and VoIP services on cargo and cruise ships, commercial and business aircraft, and remote terrestrial sites, such as oil fields and mines.

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Technical Information:

VoCeM Architecture:
VoCeM compression runs between two servers, connected by any IP link. VoCeM uses a ombination of compression, optimisation and transcoding techniques to achieve an unparalleled efficiency

Other key features of Vocem are:
- Optional transcoding into ILBC or AMR
- A wide range codecs are supported, including G.711, G.729, ILBC, GSM-FR, GSM-EFR, AMR
- Vocem uses standard backhaul compression, for example RFC 2507 and ROHC
- Vocem runs over either routers or NAT
- Runs on open source Linux kernels 2.6 or higher

There are four key stages in the process:
1) Voice packets of VoIP, GSM or UMTS are transcoded using low-rate codecs
2) Several voice packets are multiplexed in a single IP/UDP container
3) IP-UDP-RTP headers are compressed to the absolute minimum and routed via satellite to a decompressor
4) Voice packets are transcoded back to VoIP, GSM or UMTS and sent to the telephone networks

VoCeM increases the number of calls(and total bandwidth consumption in kbps. The following table compares the achievable number of calls for a certain satellite bandwidth:

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Download VoCem Product Brochure (pdf)