Preparing for the acquisition of AT&T Wireless, Cingular has committed to a $100 million deal to buy network services from AT&T, Cingular said Monday.

The deal is part of an agreement struck between the three companies involving use of the AT&T brand as part of the upcoming transition period during which AT&T Wireless will become part of Cingular. The deal covers the transition period plus another six months, the companies said in a joint statement.

“During a six-month transition following the merger, Cingular will have certain licensee rights to the AT&T brand for wireless services,” the statement said. “Cingular intends to use its own brand for the new combined company following its acquisition of AT&T Wireless, and it will cease using the AT&T brand at the end of the transition period.”

AT&T will continue to provide some services to the combined Cingular/AT&T for some 17 months. Services include international long distance, private line services, and corporate telecommunications services.