简单多了：

exports.myFunction = functions.https.onCall((data, context) => {
    const phone = context.auth.token.phone_number;
})

使用admin.auth().getUser(uid)应该可以：

const functions = require('firebase-functions');
const admin = require('firebase-admin');
....

exports.sampleFunction = functions.https.onCall((data,context) => {

  return admin.auth().getUser(context.auth.uid)
    .then(userRecord => {
      const phoneNumber = userRecord.phoneNumber;
      console.log(phoneNumber+" ***** "+context.auth.token.email+"      ***** "+context.auth.token.name);   
      return userTransaction.sampleFunction(data,context)    //Not sure what this is doing, I just chained it with the previous and next then(s). Modify as necessary....
    })
    .then(message => {
      console.log(message);
      return { message: message };
    })

});

请参阅这里的相应文档和here。注意，getUser()返回一个promise。