try this:
if you trigger the link for the call set the actual time in a localStorage-item.
$("#yourButton").click(function() {
var actualTime = new Date().getTime();
window.localStorage.setItem('callStart', actualTime);
})
after that you need to read the Storage after user ends up the call.
You can set this in the document.ready on the opening page.
in $(document).ready(function() {})
// check for the localStorageItem
if (window.localStorage.getItem('callStart')) {
// get it
var timeStart = window.localStorage.getItem('callStart');
var now = new Date().getTime();
/*
Now calculate here the difference now - timeStart
and you will get seconds, minutes or whatever you want
*/
// !!! Dont forget to clear the localStorageItem
window.localStorage.removeItem('callStart');
}
This is what I would try. The Usage of the HTML5-localStorage gives you the possibility to store key/values and data isnt lost if user stops the app or device is automatically locked.
Hope this helps a bit.
ADDED: You even can store JSON as the value in the localStorageItem. So you can set an callID and implement a calling-history for your users.