PRO Call Blocker - Ver 2.0 - Incoming & Outgoing Telephone Number Blocker Blocks up to 1,200 telephone & fax numbers (up to 16 digits each) Block up to ten (10) incoming area codes and/or prefixes (up to 10 digits each) Block up to 100 outgoing phone numbers Block calls with no caller ID information (shown as unknown, private, out of area, anonymous, etc) Line powered (does not require batteries *** please discard battery compartment). User adjustable 16-digit Caller ID display shows phone numbers (no name), date/time. Works with most telephone services (PSTN, VOIP).