Removes default SIP number.

app.js

 function callSipButtonClicked()
 {
     $.prompt('<h2>Enter SIP number</h2>' +
-        '<input id="sipNumber" type="text"' +
-        ' value="' + config.defaultSipNumber + '" autofocus>',
+        '<input id="sipNumber" type="text" value="" autofocus>',
         {
             persistent: false,
             buttons: { "Dial": true, "Cancel": false},
                 if (v)
                 {
                     var numberInput = document.getElementById('sipNumber');
-                    if (numberInput.value)
+                    if (numberInput.value && numberInput.value.length)
                     {
                         connection.rayo.dial(
                             numberInput.value, 'fromnumber', roomName);

config.js

     minChromeExtVersion: '0.1', // Required version of Chrome extension
     enableRtpStats: true, // Enables RTP stats processing
     openSctp: true, // Toggle to enable/disable SCTP channels
-    //defaultSipNumber: '20669', //Default SIP number used in call dialog
 //    channelLastN: -1, // The default value of the channel attribute last-n.
 //    useRtcpMux: true,
 //    useBundle: true,