What is an analog line?

Generally the line you get from the phone company is an analog line. It's the most common style used today for regular phone service. Digital phone lines are usually found in business offices. These can be better thought of as internal phone companies. Many businesses have several outside phone lines that come into their office, and are then processed through a key system (or PBX) with a central control unit. These systems then process the information digitally, and require separate business phones to use with their key system.