Once you enable Privacy Protection for your domain name, the Contact Details in any Whois Lookup query would display generic details.
Letters, couriers delivered at the Postal Address would not be accepted. This implies, that you will not be contactable at the address displayed in your domain name Whois.
Telephone callers would be advised to email you at the email address displayed in the Whois of your domain name.
Email sent to the email address listed in the Whois, will get a response specifying an unbranded URL, which needs to be visited by this person. Upon visiting this URL, they would be able to mention their query in a secure form, while specifying the type of Contact (Registrant, Administrative, Technical, Billing) they wish to email. The contents of the submitted form will then be emailed to the selected Contact's (Registrant, Administrative, Technical or Billing) email address, as specified in your Control Panel.
Therefore, you are assured of still being contactable, even though your Contact Details are not visible in the Whois of your domain name.