Companies have been trying to come up with an electronic means for people to buy music for two or three years now, but the boldest, IBM Corp’s technology for enabling you to get the compact disk – and track listing perchance, of your choice made up right there in the store from downloaded music streams seems to have foundered on the rocks of record company antipathy. Far less revolutionary, but probably more practical, is MCI Communications Corp’s 1-800 Music Now on-line record store announced yesterday, which takes the dear departed listening booths from the days of 78s and 45s right into the comfort of your home – at the same time cutting the audio quality right back to the 4KHz slice you get on the phone. Once you are through to MCI’s US toll-free number, you use the touch-tone telephone keypad to navigate through a vast menu to choose snippets you want to hear from a possible 20,000 songs from 5,000 abums and then order the compact disk on which anything you like is recorded. Callers will be able to listen free to as many snippets – each of only 20 to 30 seconds duration, as they want. MCI hopes to make money selling the disks and will ask customers making their first call to set up accounts by providing their credit card number and address. MCI has also set up alliances with radio stations in more than 100 US cities: the stations will promote the service, offer promotions and recommend albums. Prices are expected to be nearto those in record stores. All major labels are said to have agreed to supply MCI’s venture, which will later get rather more sexy: it will start out with a catalogue and an Internet site, and the company also plans to move to more advanced technology.