You tell PhonePeace which calls you want to receive (your Friend's List); all other calls are blocked and sent to voicemail. Automatically! No red button to push! If your number is not in the Friend's List you don't get through. | The Friend’s List holds 800 numbers and is programmable from a calculator style keypad or an Excel spreadsheet (Windows 7, 10 ,11 only). | Compatibility: Compatible with Landline phone service from a cable/internet provider like Xfinity, 1-Voip, Spectrum, others, or internet connected Landline phone services like Vonage, Ooma, Google Voice. NOT COMPATIBLE if the Landline telephone line is not connected to the internet or is DSL. If you aren’t sure, please contact us before ordering. | Ringing: If the number is in the Friend’s List, the phone rings normally. With PhonePeace System there is one ring for a blocked call. If you want no rings for a blocked call, see PhonePeaceRS on Amazon. | Answering Machines: Phonepeace works with most stand-alone home answering machines. If you have an integrated phone answering machine you use the answering machine for Friend’s List calls and phone company voicemail for blocked calls. | Stop the elderly from getting scammed, protect your relatives, and silence unwanted ringing. | 30-day full refund guarantee as long as the unit is returned undamaged with all parts. 1 year warranty. Assembled in the USA, USA Tech support, Software upgradable for latest features and functions.