Some old style home phone requires more power for ringing. Please download this firmware updated to fix this issue.
****Make sure the version number printed on the back of your device is Ver 2.0 or lower.
Download Cell2Jack App from Iphone or Android's store.
The firmware update will take 4 to 6 hours. Make sure your cellphone's power is connected before update.
After the long update, you need to reboot to have second short update ( ~ 20 min).