try Hello Buzz from google play https://play.google.com/store/apps/details?id=com.terrificmobile.hellobuzz&hl=en
If you enable Connection Vibration on your G2, the device vibrates as soon as the other party answers the call. In other words when the call is connected and the person on the line answers the phone, the device lets you know by vibration.
Enable Connection Vibration by doing as follows:
1. Open Setting and go to Networks tab
2. Open Call settings
3. Under Ongoing Call settings, make sure to enable Connection vibration.
Lean More LG G2 Tips and Tricks