Ameritech Inc is sick of always being seen as the staidest of the Baby Bells, and the Chicago telephone company is hoisting its skirts and getting into the music biz. It has paid $5m for a 20% equity stake in MNI Interactive Inc of San Francisco. MNI’s flagship product is MusicNet, a personalised interactive music and previewing shopping service available on CD-ROM and over the telephone. Ameritech also gets rights to include specialised versions of MusicNet and future MNI services via its embryonic on-line and broadband service offerings.