Plain Ordinary Telephone Service. This is the old analog telephone network that usually just one company in a region owns. For example, Verizon owns the POTS network within Allegheny County. However, since there is an expense to keeping the POTS system working, many telephone providers is shutting down the system, and requiring that calls from their service is connected to the internet. In most cases, the POTS termination point will plug into a telephone 1 / telephone 2 jack on the router, and from there – telephone service is provided. However, for this to work, you must use the carrier’s modem.
One could use other solutions for telephone services – either being cellular or Voice Over Internet Protocol services. These two options do not require the telephone company to be your telephone provider.