MCI Communications Corp, Washington will cut rates for many business services on February 1: there will be a 3.5% reduction in Prism Plus charges, with a drop in the monthly service fee to just $10 from $75; volume discounts will be increased to 10% for customers spending over $150 per month and 20% for those spending over $2,000 per month; there will be a 3.6% reduction in MCI 800 Service, including a simplified pricing structure; an overall 3.3% rate reduction for Prism I, Prism II and Prism III, including a new 5% volume discount for all interstate Prism I usage over $10,000 a month; an average 7.9% cut for Vnet usage rates and an increase to 9% from 6% in the maximum volume discount for monthly use; a 5% volume discount for Corporate Account Service Plus option for all Prism I usage and a 20% volume discount for Prism Plus use.