Is there a way to include User Identities in a Search API response?

I'm looking for a way to obtain additional User data (primary email, primary phone, etc) when requesting tickets assigned to a particular user id. 

The search API provides a way to include some of the User data in the response, but it looks like only one email and phone number are returned when doing the following type of search query:

Ideally, I'd like to get all of the email addresses and phone numbers for all the users (requester, submitter, etc) in an assigned ticket within one API request. 

The data I'm after appears to be in a User Identities API request, however this would require that I make multiple API requests for a single ticket.

Are there any suggested or simplified ways of obtaining User Identities for an assigned ticket in a single API call?