Short Answers

Short Answers Paper Week 2

The telecommunications field is a vast field that contains terms and acronyms which can be confusing to those who are not familiar with the terminology. Therefore, the following paragraphs will compare and explain some common terms used when referring to the telecommunications field and will entail some old technology with some new. To be included within the discussion is comparisons of telephone dialing sounds, Wide Area Telecommunications Services (WATS) versus leased lines, Private Branch Exchanges (PBX) or Centrex, and the International Organization for Standardization-Open Systems Interconnection (ISO-OSI) model.

What are the differences between Rotary and Dual Tone Multi-frequency (DTMF)? Rotary dialed phones were round and “spun” to make a phone call. The disk had the numbers 0-9 and one had to place a finger in the hole next to the number they wanted to select and turn the dial completely around then let go. When the disk spun back to its original position it would create a series of frequency pulses that corresponded to the number dialed and was known as “pulse dialing.” The phone company switching network would recognize the number of “clicks or pulses’ sent and would switch to the appropriate line.

On the other hand DTMF uses a “tone dialing’ method to place a call. A push button phone uses the “tone” method of dialing. Each time a number button is pushed on the phone, the circuitry in the phone makes a two toned sound for each number and sends that sound to the phone company switching network for validation and to be patched through to the correct line (Zeebar, 2007).

What are Wide Area Telecommunications Service (WATS) and leased lines and how are they different? Wide Area Telecommunications Service is a special “dedicated” line for individuals or company’s that want to have to luxury of having a designated number that would allow for incoming calls to be received at no charge to the customer. Furthermore the WATS system usually comes with a discounted price for its use due to the expected large volume of calls (Shired, n.d.).

Leased lines are different from WATS in the sense that they are borrowed lines and are used only by those who have leased the lines. What this means is that the line is open for use by the leaser anytime the leaser needs the line to communicate with. Additionally, the phone company does not use the line that is leased to conduct other phone services on and leaves the line “open” for the leasing company only to use for communication (Mitchell, 2008). On the other hand, a WATS line is used repeatedly by the phone company while still being used by the client who pays for the WATS.

How do Private Branch eXchange (PBX) and Centrex differ? A PBX is a company centered switching network for in-house calling. The company would typically have a few dozen phones within the network and each with a need to be able to complete in-house and outside phone calls. With a PBX an employee could call another office within the company by simply dialing a few digit phone extensions rather than a full phone number. Additionally, when these types of calls are made it does not interfere with outside phone lines or take up any of the space of outside phone lines. All the phone lines are maintained within the company itself with just a few lines to connect to the outside phone network for outside calls (Webopedia, 2003).

A Centrex (Central Office Exchange) is different from a PBX simply by the location of the switching operations. A Centrex switching is off site from the company and is run and operated by the local telephone company. With that said, the PBX equipment would have to be bought, installed, and maintained by the company where with a Centrex all that would be done by the providing telephone company (Webopedia, 2003).

The International Organization for Standardization-Open Systems Interconnection