Prospect/Contact data not populating to a new Opportunity when converting

Prospect/Contact data not populating to a new Opportunity when converting

Pls can you help me as to why all data entered onto a Prospect's record doesn't pull into the Opportunity record when I convert it? eg. the phone number & the email address sometimes don't automatically populate - & this means that the functionality re calling/emailing out directly from the Opportunity record doesn't work