I've never seen this done before. Not saying it can't be, but there is no native "app" processing in the tool. If you could send the content to an email address, it's likely that the system will pick it up from the email and process it.
From ServiceDesk you may use data connection and data import from textfile or database. Paln to run the service each 10 minutes to receive messages quickly. But the main problem is to put whatsup messages or sms messages in a textfile. Your telecom operator may provide sms API to read and send API as french Orange does. For WhatsApp it may be more difficult as WhatsApp does'nt want to allow mass WhatsApp messages and does'nt support APIs. Additional information here : Create a web service that can answer to WhatsApp messages - Stack Overflow