For Online surveys we will only contact you using your email address you supplied.
For Discussion invites we will usually contact you initially via your email address you supplied. This will be followed up by a phone call to the number(s) you have provided if it looks like the discussion or interview is relevant to you. We may also contact you by sms to advise you of a questionnaire or ask you to call in if you think you might qualify for a discussion group.
At any time you can Opt out of being contacted by Email/Phone/SMS. However if you opt out of receiving Emails, this will mean your account will become inactive until you Opt back in as the Email is the primary point of contact for both Online and Discussion Groups/Interviews.