MCI Telecommunications reported that it has begun to offer 24-hour customer service in California, Nevada and Hawaii. . . Pacific Southwest Airlines reported that it flew 366.1 million revenues passenger miles in March, up 24.2% from a year earlier. . . The United States, in response to appeals from Latin American governments, decided to continue taking part in the International Coffee Agreement despite misgivings about it, U.S. officials said. . . The Investment Company Institute reported that the assets of the nation's 357 money-market mutual funds rose $681 million in the week ended April 2.