Lookup Search API Freshsales

We are working on a custom CTI app, where we need to search for contacts based on name or phone number the agent enters in their dialpad. The problem we face is that, we are unable to search the contact’s name and Phone Number using the Lookup or search API.
There are no much info on the document related to it.
Could you please advice on how to use the right operator and the exact attribute to look up contact name and Mobile Number in Freshsales?

Any help on this would be greatly appriciated.