On Schoolrunner's Groups page, you can filter for all students that are in a course, or even a particular section. You can then export details for these students, including address and primary contact number. Note, however, that different schools store contact numbers in different fields, so be sure to check that the primary contact number included in this export lines up with the right number on the respective student's page. (All contact details are visible on a student-by-student basis on individual student pages.)