What is the Category Rating System?
In the mid 1980’s, companies representing the telecommunications and computer industries were concerned with the lack of a standard for building telecommunications cabling systems. In response to that concern, the Electronic Industries Association (EIA) developed a standard called TIA/EIA-568-A.
One of the sections of that standard was the definition of performance categories for 100-ohm UTP horizontal cabling.
Level 1 This category consists of basic telecommunications and power-limited circuit cables. There are no electrical performance test or bandwidth requirements for this classification. Level 1 cabling may not be used in horizontal cabling systems.
Level 2 This category consists of cables specified to 1 MHz. Level 2 cabling may not be used in horizontal wiring cabling systems.
Category 3 This is a performance designation for twisted-pair cable and connecting hardware that can support frequency transmission up to 16 Mhz, and data rates of 10 Mbps. Category 3 has the capability to support low speed data applications, performing to the acceptable minimum for 100 ohm cabling systems; however it is now primarily used for telephone wiring.
Category 4 This category consists of cables and connectors specified up to 20 Mhz and data rates of 16 Mbps. Since the development of Category 5, however, Category 4 wiring systems are rarely used.
Category 5 This category consists of cables and connectors specified up to 100 Mhz and data rates of 100 Mbps, providing optimal performance for all data and phone systems. These systems are quickly becoming the standard because they provide a "safety net" to help ensure that current and future high-speed applications will run with peak accuracy, efficiency and throughput.
What is POTS?
Plain Old Telephone Service (no kidding!) – The most basic of phone services utilized by most homes and businesses for phone service. Known as standard dial tone. In business applications, POTS is usually priced at Key Line Rates (phone lines going into a key phone system).
What is ISDN?
Integrated Services Digital Network – ISDN service provides simultaneous, high-speed digital transmission of voice, data, and video over existing telephone lines. With ISDN, customers ca n utilize multiple functions, such as faxes, voice, data, and internet access through a single line.
What is DSL?
Digital Subscriber Line – DSL is a high-speed data service usually utilized for internet access, both residential and business. DSL comes in many variations – ADSL (Asymmetrical…) where the speeds for downloading are usually much faster than upload speeds; SDSL (Symmetrical…) which has the same speeds for both directions; IDSL (Integrated…) which maintains the same speeds as a bonded ISDN line-128kbps. DSL is becoming much more prevalent and user-friendly all the time, but it has distance limitations and a customer can only be so far from a served-central office and must have a "clean" line to run DSL upon.
What is a T1 Line?
T1 is a member of the T Carrier family. Originally called a T1.5, the "T" was used by AT&T to distinguish between a terrestrial network as opposed to satellite. T1 is a standard 1.544Mbps (Megabits or million bits per second) carrier system.
What is a T1 used for ?
There are different types of T1 Lines. They can be used in a variety of ways:
Dedicated T1 Internet access - A dedicated T1 connection to the Internet is a high speed connection that is always on. It's comprised of a T1 local loop that takes you to the ISP's Point of Presence (POP) and a full T1 speed connection to the Internet at the POP. U nlike dial-up, DSL, cable or satellite, dedicated Internet access usually carries a Service Level Agreement (SLA) that guarantees at least 99.9% of the T1 bandwidth will be available to you at least 99.9% of the time or you will be refunded for a portion or all of the days on which full access was not acheived. Unlike all the other mentioned types of Internet access, dedicated access, properly delivered, is never shared, thus always providing you with maximum speed that should rarely be subject to the slow downs shared services experience at peak hours.
- Dedicated T1 Long Distance Service - It is sometimes possible to bypass the local telephone company by leasing a T1 local loop directly to your long distance carrier's switch.
- T1/PRI Local Service - T1 local service is an alternative to using many individual pairs of wires to bring in a large number of phone lines. One T1 carries 24 voice lines over one set of 4 wires. There are other advantages as well, such as digital quality, fast call setup and, sometimes, access to better local and/or long distance rates.
- Private Line - a private dedicated "inter-office" circuit that is always on and is used to carry voice or data between 2 locations. Businesses, ISP's, local and long distance telephone companies use private lines T1's to carry voice, data or a combination thereof from one location to another.
- Local Loop - A local loop is the "last mile" or last leg of the route required to deliver service to and from the telephone company, ISP, cable company or other service provider's central office or head end equipment. In the case of a long distance or local service T1, the local loop is a private line that you lease for a flat monthly fee which delivers service to and from your local or long distance carrier's switch.
- Frame Relay - A "packetized" data service/protocol used for private networking and local loop transmission protocol for access to the public Inter net.
What is the difference between Analog and Digital Phone lines?
As a technology, analog is the process of taking an audio or video signal (in most cases, the human voice) and translating it into electronic pulses. Digital on the other hand is breaking the signal into a binary format where the audio or video data is represented by a series of "1"s and "0"s. Simple enough when it's the device—analog or digital phone, fax, modem, or likewise—that does all the converting for you.
The newer of the two, digital technology breaks your voice (or television) signal into binary code—a series of 1s and 0s—transfers it to the other end where another device (phone, modem or TV) takes all the numbers and reassembles them into the original signal.
How can I tell if I my phones are analog or digital?
Look at the back of the telephone connected to it. If you see "complies with part 68, FCC Rules" and a Ringer Equivalence Number (REN), then the phone and the line are analog. Also, look at the phone's dial pad. Are there multiple function keys? Do you need to dial "9" for an outside line? These are indicators that the phone and the line are digital.
What is a REN?
Ringer Equivalency Number - A number representative of the maximum voltage that can be carried by a single Central Office (CO) phone line. In most cases, the CO offers a maximum REN of 5. The amount of REN required by an individual analog telephone is usually listed on the bottom of the phone. If REN is exceeded it will result in the loss of ring capability in certain phones.
The FCC decreed that the subscriber would be responsible for the 'load' their CPE (Customer Provided Equipment) devices put on their phone line. Some guidelines were established:
- Each device will have a REN ,"ringer equivalency number", marked somewhere on the device.
- The total of all of the RENs on any phone line can not exceed 5
- Devices that ring at 20 Hertz will have a suffix of 'A' added to the REN
- Devices that ring at any frequency will have a suffix of 'B' added to the REN.
Typical analog phone lines have 85 to 105 Volts A.C. superimposed on a nominal -48 Volts D.C. The A.C. current during the ringing cycle is between 20 and 50 milliamps. It will give you a shock!
What are common clamping voltages for different types of lines?
Clamping Voltage Description 5 Volts T1 Lines; Internal digital data systems; ISDN Lines 36 Volts Alarm Systems; Pager Bells; Broadcast System Speakers 60 Volts "POTS" (Plain 'Ol Telephone Service); Leased lines; PBX Phones 200 Volts "POTS" (Plain 'Ol Telephone Service) from Central Office Lines (most common "standard" phone systems)</ td> NOTE! Standard phone lines can have different voltages. They are commonly the "200 Volt" Clamping variety. If you cannot tell the difference, you should use suppressors clamping at 200 Volts. It will not provide the best protection possible for systems that should have 60 Volt clamping voltages...but it is far better than nothing and will protect most systems adequately.
What are the different connectors used?
|RJ-11/12||6 Position Modular Jack (Often called an RJ11 or RJ12 jack or plug.)|
|RJ-45||8 Position Modular Jack (Often called an RJ45 jack or plug.)|
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Last Updated: 07 Jun 2004
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