SENTRY 3.1 Call Screener, smart active blocking, block all solicitor calls, election calls, robo calls. Unique ACTIVE screening, blocks all unknown or known spam calls. Fully automatic blocking after set up. Set up Whitelist (friends and family) with keypad. (New feature)REQUIRES Caller ID service. No need to take a bad call and then block it. No more bad calls, period. 100% effective on all robo calls, election calls, telemarketing or any solicitor calls. Record your own out going message in any language. (New feature).