June 16th 2011 marks IBM's 100th anniversary.
IBM and its predecessors have been involved with the telephone industry since their beginning. Western Electric supplied relays in the early days. IBM worked with the Bell System to develop data communications in the 1940s onward. In the 1960s the line between communications and data processing blurred, resulting in various FCC computer decisions. In the 1980s the world wondered if IBM and Bell would be competitive rivals.
IBM offered private network telephone equipment in the 1930s-1940s. This apparently was sold off when IBM discontinued its time-clock equipment business.
In later years IBM owned Rolm, a telecommunications equipment maker.
more info
formatting link