You have to add an ICS file to your confirmation email.
1) go to Outlook and create a calendar item that you want the participants to save.
2) open the agenda item -> go to file -> choose save as -> put it eg on your desktop and give it a name. For example the congress name. The file is now called 'Congress name.ics'
3) go to the participant module online -> mailings -> participant registration mail -> edit and add the ics file as an attachment.
4) make a test registration and test whether you can indeed put the conference in your agenda via the attachment.
You can also forward the mail to your hotmail/gmail/yahoo to see if you can save it in your phone calendar.