The requirements for collecting GMI on a telephone application are dictated in Appendix B to Part 1003 under #11, 12, and 13 – Link.
If the application is taken by telephone and the applicant elects to not provide the information then you would report “information not provided by applicant in mail, internet, or telephone application.” If you later meet with the applicant in person during the application process then you are expected to collect the race, ethnicity, and sex based on visual observation or surname; however, you do not collect the subcategories, only the aggregate categories.