What is "diversi-dial"

Diversi-Dial, or DDial was an online chat server that was popular during the mid-1980s. It was a specialized type of bulletin board system that allowed all callers to send lines of text to each other in real-time, often operating at 300 baud. In some ways, it was a sociological forerunner to IRC, and was a cheap, local alternative to CompuServe chat, which was expensive and billed by the minute. At its peak, at least 35 major DDial systems existed across the United States, many of them in large cities. During the evening when telephone rates were low, the biggest DDial systems would link together using Telenet or PC Pursuit connections, forming regional chat networks.