Arrange a time for when the students can come as a group and visit your business. There might be systems they have to review, or employees they may need to meet. Set a deadline for when they are to present their results. Students need to understand business deadlines. You are a businessperson and you have other priorities, but there might be follow-up questions.
Electronic mail is a great method of communication.
Perhaps you can designate a certain time of the day when you might be available for phone calls. Resist the temptation to micromanage the students, or try to guide them through the process. If you leave them alone, the results are far more interesting. Set aside about an hour for the final meeting. The students typically will give you a verbal report, as well as a written one.