There are many issues to consider when completing an ethics application.
The information contained within the Deakin University Human Ethics webpages may answer your questions.
Data Anonymity and confidentiality
Sometimes there is confusion regarding how data are classified. Data may be individually identifiable, re-identifiable or non-identifiable (refer to the National Statement, Chapter 3.2). Please ensure that you are clear to your participants about the confidentiality and anonymity of any information that they supply to you. You must also consider the implications if a participant withdraws from a project. The level of anonymity may make destroying or not using the data they have supplied to you impossible and this should be made clear to participants prior to their involvement in your project.
What information can I give to participants, for example in the PLS or in an advertisement?
For the safety and privacy of researchers, Deakin University does not allow home landline telephone numbers to be used. You may supply a mobile telephone number, a Deakin University landline number to participants and an email adress. However, please be advised that there are also privacy issues related to the use of emails of which you should be aware.