Denver--Qwest Communications International, Denver, a young, high-flying communications carrier, is making the brashest telecommunications move in years, according to The New York Times. Qwest announced Sunday it was making a hostile, $55 billion bid to acquire U S West, Denver, the old Baby Bell local phone giant, and the Frontier Corp., Rochester, N.Y., one of the biggest long-distance companies in the nation. Qwest is trying to take U S West and Frontier, formerly Rochester Telephone, away from one of its main rivals, Global Crossing Ltd. of Bermuda. Like Qwest, Global Crossing has built a multibillion-dollar business in recent years by exploiting the surging worldwide demand for electronic communications. Just last month, U S West agreed to merge with Global Crossing in a stock deal that the company then valued at $37 billion. Frontier agreed to be acquired by Global Crossing in March for $10.8 billion in stock. Now Qwest wants to win them both.