POTS, or Plain Old Telephone Service, Copper Lines, CO Trunks, all of these are names for the same service, telephone lines from your local carrier. This may be Verizon, ATT, or any number of large telephone companies that have provided this basic service for homes and businesses for decades. This is the typical type of service that most businesses start out with. These lines cost a business anywhere from $30 to $50 a month depending on the location and features provided by the telephone company.
Most telephone systems can accommodate this type of service. However, it can get costly fairly quickly. As you can see, once you have more than a couple of lines the monthly cost gets pretty high. At this point it would be good to look at our next type of service, T1 or PRI.