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

This logic and flow is kind of wonky. In general, it's better to write all-encompassing conditions like this:
```js
if (call.state !== 'connected' || !dtmfDigits || !dtmfDigits.length) {
  return;
}
```