POTS  - stands for Plain Old Telephone Service (seriously).  This is an analog service that is provided via copper wires and is what most people have in their homes.  The advantage to pots service is that it is inexpensive to deliver AND the electricity is provided by the phone company over the copper wiring.  This is an ideal service for small business and many large companies use pots service as a backup in the event of a power outage. 

Pots service can sometimes be susceptible to static but it is more survivable in bad weather conditions because it is not a digital service.  However, pots service is typically last in the chain of repair and the least experienced technicians are dispatched to repair it.