Plain Old Telephone Service

Plain Old Telephone Service, or POTS, are the services available from an analogue telephones prior to the introduction of electronic telephone exchanges into the public switched telephone network. These services had been available almost since the introduction of the telephone system in the late nineteenth century.

These services included:

• Bi-directional, or duplex, speech path,
• Dial Tone and Ringing Signals[?],
• Subscriber Dialing,
• Operator Services, such as directory assistance and long distance and conference calling assistance.

With the advent of electronic telephone exchanges and computerisation during the 1970s and 1980s, a raft of new network services became available. These had been termed PANS for Pretty Advanced Network (or New) Services by some in the industry, although that term has never really caught on. The service offered include:

• Voice Mail
• Caller Identification
• Call Waiting
• Reminder Calls
• (Three Way) Conference Calling
• Enhanced 911

and a number of other similar services.

The new services were made possible by the introduction of the support network for the ISDN as well as raised consumer expectations from services offered on mobile telephones.