ITC Inc. of Salt Lake City has signed an agreement that will allow TIE/Communications Inc., Shelton, Conn., to acquire a majority of one ITC subsidiary, Intermountain Telephone Corp., and a minority portion of another, AutoNet Management Inc.

Under the agreement, according to Steven L. Olson, ITC Inc. president, ITC will be indemnified or released from any obligation for Intermountain's debts and liabilities and TIE will pay ITC $1.35 million cash less amounts ITC previously borrowed on several secured promissory notes.TIE will acquire 90 percent of the outstanding shares of common stock of Intermountain Telephone Corp. and will acquire 19.9 percent interest in AutoNet.

Intermountain is ITC's interconnect operating company and provides telephone equipment and service to customers. During 1987, Intermountain acquired the interconnect business from Skaggs Telecommunications Service Inc..

AutoNet is just getting started in business and is ITC's company for marketing long distance services to trade associations and other business customers, Olson said. Another subsidiary, ITC Networks of Utah, operates a long distance service for Intermountain's interconnect clients and will remain an asset of ITC.

Alan M. Williams, executive vice president of ITC, will become president of Intermountain and remain a board member and consultant to ITC.

The agreement is subject to certain closing conditions and ITC's shareholders who will hold a meeting May 6.