CallClerk is described as 'Windows software that uses modem to record Caller-ID, Block phone numbers on a banned list, act as an answering machine and fax machine, and dail phone numbers'. There are four alternatives to CallClerk for Windows. The best alternative is Call Station, which is free. Other great apps like CallClerk are PhoneTray (Paid), SmartCallMonitor (Free) and W7 Caller ID (Paid).
Full-featured telephone utility with an advanced answering machine, phone dialer, contact manager, fax receive capability, and optional Caller ID and speakerphone support. (requires a USB callup modem with voice/fax/data/caller-id.