Minneapolis, Minnesota-based MultiTech Systems Inc is beginning European shipping of a Personal Communications System it claims will enable simultaneous voice and data over a single standard telephone line. The system is based on the MultiModemPCS, a combination V.34 data and V.17/Group 3 facsimile modem, first released in the US last year. The voice functionality comes with the company’s Talk AnyTime hardware, which ships with MultiModemPCS. This feature turns the modem connection into a point-to-point speech and data packet network when an attached handset is picked up. The mechanism for this is the firm’s own MultiTech Supervisory Protocol, which enables a header in each packet to identify the packet’s contents and destination. The MultiExpressPCS software, included in the product, then determines the type of incoming call and launches the appropriate software via a Virtual Modem Driver. For voice calls, MultiExpressPCS turns the personal computer into an answering machine. As a speech and data connection, speech and data packets are transmitted as they are presented to the modem, with priority given to voice packets, providing simultaneous voice and data communications, says the firm. The data packets are sent during ‘quiet times’ of speech, which account for up to 60% of total time connected. If there is a pause in speech that lasts 100mS, data is sent at 115Kbps, says MultiTech, with higher throughput possible if V.42bis compression is used. Also bundled with the package is TalkShow document conferencing software, enabling users to display and interactively change a document over a link. MultiTech says competitor Radish Communication System Inc’s VoiceView uses a start-stop technique that sends voice or data while turning off the other, entailing retrain requirements of up to 250mS. The company also claims the maximum transmission rate of VoiceView is 9,600bps, against its 115Kbps. European roll out will begin next month in the UK, where the price will be UKP800.
