If you do not have a dial tone on your phone when you have the Call Blocker connected, this will be due to set up.
Please make sure that you are using you main telephone cable that was previously plugged into your telephone base unit and wall jack/modem/router.
The end of this cable in the phone needs to be removed and placed into the LINE port of the call blocker. The end in the modem/router/wall jack stays in there it is not removed. Then using the BLACK cable provided with your purchase, place one end into the TEL port of the call blocker and the other end into your telephone base unit.
Check you have a dial tone, and press and hold the BLOCK NOW button down for 10 seconds till it beeps, then hang up the phone.
If you are still having issues and do not have a dial tone, check the cable from the wall jack/modem/router is connected fully. If this still does not resolve the issue, remove the black cable from the call blocker and the phone and use the white cable provided with a red end. Place the RED end into the LINE 1 port of the call blocker and the other end into the phone, this will set it up in Parallel but will enable the dial tone and Caller ID to be visible.