Plain Old Telephone Service (POTS) Overview
Plain Old Telephone Service (POTS) is a standard telephone service used in most residential homes and some small businesses. However, telephone services based on high-speed, digital lines are not under POTS. Compared to Non-POTS, POTS is generally restricted to 52 Kbps. POTS network is also called the public switched telephone network (PSTN).
POTS is a retronym reflecting a telephone service still available after the introduction of more advanced forms of telephony such as ISDN, mobile phones and VoIP. It has been available almost since the public telephone system in the late 19th century. It is in a form mostly unaffected even with the introduction of Touch-Tone dialing, electronic telephone exchanges and fiber-optic communication into the public switched telephone network (PSTN). It was originally known as the Post Office Telephone Service or Post Office Telephone System in many countries. But with the removal of control of national post offices in telephone services such terms are not used.
Nowadays, new forms of communications devices like modems and facsimile machines are intended to use POTS to transmit digital information. This is mainly due to the wide availability of POTS.
- Bi-directional, or full duplex, voice path or a signal that carries the sound of the human voice both ways at once with frequency range of 300 to 3400 Hz;
- Call-progress tones (dial tone and ringing signal);
- Subscriber dialing;
- Operator services (directory assistance, long distance, and conference calling assistance);
- Standards compliant analog telephone interface including BORSCHT functions
POTS Calling Features
- Voicemail - sometimes called as message bank. It is a centralized system that handles telephone messages. It is also used to represent any system of conveying voice message including the answering machine.
- Caller ID - known as caller identification (CID). It is also more properly know as calling number identification (CNID). It is telephone service that passes on the number of the caller to the telephone equipment of the called party during the set up of the call and before the call is answered.
- Call waiting - is a feature on some telephone networks that allows a called party currently engaged in a phone conversation to suspend the current call and switch to the incoming call. This can be done by pushing the flash button.
- Speed dialing – is also known as abbreviated dialing used with very short telephone number to reach public services. Usually these are two or three digits that are commonly referred to as emergency telephone numbers like 9-9-9, 1-1-2 and 9-1-1. Its main purpose is to be universal, short, and easy to remember.
- Conference call (three-way calling) - is a telephone call with more than one called party to listen in to the audio portion of the call. Three-way calling, on the other hand, usually entails an extra charge. This is done when the first person one wishes to talk to is dialed followed by pressing the Hook flash and the other person's phone number is dialed. During the ring, flash / recall is pressed again to connect the three people together.
- Enhanced 911 – a telecommunications based system that mechanically combines a physical address with the calling party's telephone number, and directs the call to the most appropriate Public Safety Answering Point (PSAP) for that address. The caller's address and information is displayed to the call taker immediately during the call. This provides the location of the emergency without the person calling for help. Where communicating one's location is difficult or impossible, this feature is very helpful especially during emergency cases such as fires, break-ins, kidnapping, and other unanticipated events.
- Centrex - a kind of telephone exchange (central exchange). It is a PBX-like service that switches a call to the central office instead of the customer's premises. All the communications equipment and software necessary to implement the Centrex service are owned and managed by the telephone company.