Bug 911055 - [zffos1.1][P3][Dailer]DuT doesn allow to dial a <<pause>>

```javascript
var DTMFdigits = DTMF.getDTMFdigits(sanitizedNumber);
if (DTMFdigits) {
  // No need to rewrite the onconnected method with this
  call.addEventListener('connected', function() {DTMF.play(DTMFdigits) })
}
```
This seems simpler and should be the only thing done in TelephonyHelper (with the new regexp)