Error getting user's phone number through ZAF Client

I am using ticket.requester.phone as the placeholder in my app which is supposed to pull a user's phone number and then search my company's API for their info to display. I keep getting the error

InvalidPathError: Path 'phone' doesn't exist on node ‘requester’

Does anyone know another way to pull this? It works just fine using ticket.requester.email

const client = ZAFClient.init();
client.invoke('resize', { width: '100%', height: '300px' });
let phone_number;

// Use the Zendesk app client to get the ticket requester's phone
client.get('ticket.requester.phone')

.then(async function(data) {
  const phone_number = data['ticket.requester.phone'];