As a self-employed person, you can always change your contact details such as your telephone number and e-mail address on My Liantis.
Navigate to the theme 'Ik als zelfstandige' and then click on the tile 'Mijn sociaal statuut'.
Once in 'Mijn sociaal statuut', click on 'Mijn profiel' - 'Mijn contactgegevens'.