ATLANTA (AP) _ United Parcel Service said Monday it plans to use mobile phone technology to allow it to track packages from pickup to delivery.

By early 1993, 50,000 UPS delivery trucks will carry cellular equipment to transmit package tracking information through the company's new telecommunications network, UPS said.

The $150 million project will include in-vehicle communications equipment developed by Motorola and network services provided by McCaw Cellular Communications, GTE Mobile Communications, PacTel Cellular and Southwestern Bell Mobile Systems.

''We selected cellular instead of existing radio networks because of high network reliability, the widest geographic coverage and the most promising migration to future mobile data technologies,'' said Gene Hughes, vice president of strategic technology planning for Atlanta-based UPS.

The network will provide immediate access to delivery information for more than a million UPS daily pickup customers, the company said.