How to get contact information of user logged in to Customer Center

Hi,

I've developed two Suitelets for our customers which they can access through the Customer Center.

I'd like to add some functions that would need to store information on the logged in user's Contact record based on user input. But I've run into an issue. When using either of the below functions, the returned user ID belongs to the customer record, not the contact:

var context = nlapiGetContext();
var userID = context.getUser(); // returns internal id of CUSTOMER
var userName = context.getName(); // returns display name of CUSTOMER

Same when using the direct API:

var userID = nlapiGetUser(); // returns internal id of CUSTOMER

On the other hand, the email address works as intended: