StarCD

StarCD was a short-lived service of a short-lived dot com company called Connexus. It was a service using the Comcast Metrophone and BDS radio-monitoring data. In test markets those customers could press the buttons *CD (*23) and a short menu would direct them to select the station they were listening to and it would tell them what the song was with an audio clip. Then it gave the option to buy the CD on Amazon.com.  In the era before downloadable music and smartphones that was pretty cutting edge.

"*CD uses a patented computer technology to monitor radio broadcasts and identify songs as they air. Before new music is released, a master recording is obtained from the record companies and scanned into the systems computer-- creating a unique digital fingerprint. *CD's computers monitor local radio stations ever day of the week, every second of the day--processing the digitized broadcast and comparing it with thousands and thousands of patterns. Once a song is recognized, the sytem records the exact time, date, and station on which it played."

Connexus had only one test market that I'm aware of—Philadelphia. Their test panel was limited to WXTU, WMMR, WSTW, WYSP, WXXM, WPST, WUSL, WPLY, WBEB, WIOQ, WYXR, and WDAS. 

But the service hit some snags. Comcast wanted out of the cellphone business. They acquired AMCELL in 1988 and Metrophone in 1992 but by 1999 was backing out. While the *CD was ramping up in 1999 Comcast was selling Metrophone to the San Antonio-based SBC Communications. More here. Connexus struggled for a few more years and then found new life as a part of radio-monitoring platform serving ASCAP and Yes networks called Mediaguide. By the time the iPhone came out in 2007 StarCD was long dead. In some ways it predicted later smartphone apps like Shazam, but it was too far ahead of it's time.