Merging voice with the Internet

End product: SkyGate 98
   Voice-over-Internet gateway
   by SkyWave Inc.
TI DSP: TMS320C548
Third-party product: VIPER-12
   board by DSP Research
   (DSPR)
Success achieved: High-
   performance multiprocessing meeting the circuit-to-packet-switching demands of a multichannel VoIP gateway.

SkyWave’s SkyGate 98™, a PC-based Voice over Internet Protocol (VoIP) gateway, acts as a bridge between conventional telephone systems and the Internet, allowing voice traffic to traverse phone-to-network boundaries seamlessly. SkyGate 98 accepts multiple voice data inputs coming from the analog telephone network, then digitizes, compresses and converts this data into IP packets for delivery over the Internet.

At the heart of the SkyGate 98 system is the VIPER-12 board from DSP Research (DSPR). Packed with 12 high-performance TMS320C548 DSPs, VIPER-12 offers the processing power needed to meet the demands of a high-density VoIP gateway. The VIPER-12 delivers up to 60 channels of voice data, allowing each SkyGate 98 to deliver up to 960 channels of high-quality phone service over the Internet.

The VIPER-12 provides a multipoint crossbar switch that routes voice channels to any of the on-board DSPs. The DSPs compress each voice channel to as little as 5.3 Kbps and perform DTMF detection, echo cancellation and silence compression. SkyGate 98 offers G.723.1 or G.729a voice compression options, as well as G3 fax.

A host PC packetizes the compressed data, adds the appropriate H.323 and IP headers and reassembles packets received through the Internet. The gateway compensates as necessary to ensure a continuous data stream for outgoing voice.

SkyGate 98 also includes Natural MicroSystems’ AG-T1/E1 cards to interface to digital trunk lines, or AG-8 cards to interface to and digitize voice from PBX and analog lines.