WASHINGTON, Sept 22 (Reuters) - U.S. Treasury Secretary Janet Yellen spoke with British finance minister Rishi Sunak on Wednesday about ongoing global tax reform efforts, and underscored the need for a compromise on withdrawal of digital services taxes, the Treasury said. Yellen also thanked Sunak for his leadership of the G7 and in talks on a new tax framework under the leadership of the Organization for Economic Cooperation and Development, Treasury said in a readout of the call.