Radish: data over your voice line - Radish Communications' low-cost VoiceView protocol delivers 9600-bps data during a voice telephone call - one of several articles on Personal Data Interchange technologies

RELease 1.0, Sept 23, 1993 by Jerry Michalski

If we want to enable people to hit a key on their telephones that transmits their name and number to someone else in computer-readable form, we need a protocol for transporting data signals over ordinary phone lines during an analog call. One option is multiplexing voice and data over the same line, but so far, that requires hardware that is expensive enough that it probably won't be in consumer devices soon. Another option is ISDN, which depends entirely on telecom carriers upgrading their equipment, and will take a long time to roll out (though it is gaining momentum).

The January issue of Release 1.0 described a third option, Bellcore's Analog Display Services Interface (ADSI). But ADSI, while useful, is functionally impoverished since it was designed so specifically for screen phones. It runs at a mere 1200 baud, transmits only text in half-duplex mode and is asymmetric: A service provider (such as a bank) sends full ASCII characters and control codes to the screen phone, which replies only in touch tones -- ADSI's designers assumed that a caller has only a phone keypad. (With upcoming PDAs, callers will have RISC processors and DSPs!)

VoiceView, a protocol that Boulder-based Radish Communications created to send data and images between users having telephone conversations enhanced with Radish terminals, may be a better option for the near term. Radish's founders, Dick Davis and Theresa Szczurek, originally worked on ISDN at Bell Labs. After leaving the Labs in 1990, Davis called a travel agent, who read information off his screen while Davis took copious notes and grew increasingly frustrated. So Davis resolved to create a better way of conducting business over the phone that could benefit from shared displays of data, such as conversations with a stock broker or travel agent. The company name 1s a play on Davis' initials (Richard A. Davis).

"The more you can pack into a call while you're having the call, the better."

-- Dick Davis, Radish

Radish users can send each other data files quickly (though they can't simultaneously edit them on-screen, a desirable feature). In fact, one caller can upload a file or several screens of information to another Radish user's voicemail. When the second user gets the message, she can have her Radish system detect and interpret it. Voicemail acts as a tape recorder.

VoiceView inside?

Radish currently sells a full line of hardware and software products, including desktop terminal devices called VoiceView Sets for people without pcs, the modem-like VoiceView Bridge for those who have pea and the VoiceView protocol itself. Fortunately, Davis recognizes that the hardware is not the point, and is working to turn the VoiceView protocol into a lingua franca for sending data over the phone by licensing it broadly. In fact, he has closed enough business that by next year he expects many devices to embed VoiceView capabilities, from moderns to PBXes, voice-response and -mail systems, smart phones and PDAs. With DSPs becoming more common on pc platforms, Davis expects a software-only version to be popular, too. That seems to be the most compelling option, but Radish will continue manufacturing hardware as long as it is profitable and others don't make better competitive products.

VoiceView is a proprietary, inexpensive. reasonably quick (9600-baud. plus compression), two-way voice and data protocol that allows devices that use it to send or swap information during a voice call. Radish is making the technology available through licensing, roughly similar to the way Microcom licenses MNP, the modern data-compression protocol. During a call, the voice part of the session is completely normal, and remains analog. When the user invokes a data message, VoiceView mutes the voice channel briefly and takes over the full connection bandwidth. It is optimized to synchronize, transmit and error-check quickly: A screenful of text takes under three seconds.

VoiceView is used only when it is needed. Placing and managing a call remains unchanged. This means potential equipment cost savings, because PBXes with VoiceView processors attached could serve many simultaneous callers. few of whom would need VoiceView services at the same time. (In fact, some early PBX implamentations use the PBX conferencing feature to bring in VoiceView features.) This means a circuit- and board-level vendor such as Dialogic or Natural MicroSystems could make an attractive business of selling VoiceView adjunct systems.

VoiceView is not for a11 applications. It is designed for sending bursts of data (e.g., a screen shot, a file, my address info), not constant control signals such as cursor movements in a word processor or interactive game. Unlike ADSI. which can detect phone-system control commands such as busy signals or calling-card approval ("bong") tones, VoiceView assumes that a call is already established, with one exception: It will auto-answer a call and receive information.