Pacific Telesis Group is expected this week to announce sale of its $1m-a-year PacTel Spectrum Services unit to IBM. Spectrum Services, in which PacTel is reported to have invested some $30m, is a network trouble-shooting and fault isolation system, and its acquisition would complement IBM’s own NetView products and enable the company to offer full-scale network management services not only to users of its own equipment, but to customers with kit from a variety of vendors.