Chapter Questions
Describe the basic limitation of using the telephone system in computer communication.
List the three signal levels that telephone circuitry must work with.
Describe the sequence of events taking place when a telephone call is initiated through to its completion.
Transcribe your phone number into the two possible electrical signals commonly used in the phone system.
What is a private branch exchange (PBX), and what is its function?
List the BORSCHT functions.
Explain the causes of attenuation distortion.
Define loaded cable.
What is a $\mathrm{C} 2$ line? List its specification.
What are repeaters and when are they used on a T1 line?
Define attenuation distortion.
Define delay distortion and explain its causes.
Describe the envelope delay specification for a 3002 channel.
Why are telephone lines widely used for transmission of digital data? Explain the problems involved with their use.
What is telephone traffic? What is busy-hour telephone traffic?
What are the two units used to express telephone traffic?
What is congestion?
What is grade of service? How do traffic engineers interpret or look at grade of service?
How is grade of service measured? What does it mean when this figure is very low?
What is the significance of continuously observing and measuring traffic?
Describe the differences between an asynchronous and a synchronous communications channel. Provide examples for each.
Describe the purpose of a communication protocol.
In what ways is coded voice transmission advantageous over direct transmission? What are some possible disadvantages?
Define coding and bit.
Describe the characteristics of the four basic encoding groups: NRZ, RZ, phase-encode binary, and multilevel binary.
Sketch the data waveforms for 11010 using NRZ-L, biphase M, differential Manchester, and dicode RZ.
What are the differences between bipolar codes and unipolar codes?
Which coding format is considered to be self-clocking? Explain the process.
Describe the time-division multiple access (TDMA) technique for transmitting data over a serial communications channel.
What is the purpose of guard time and why is it necessary to provide this in a TDMA system?
Draw a block diagram of a TDMA system. Are there any special requirements for the multiplexing frequency? Describe what is required.
List the data rates for the $T$ and DS carriers.
How many telephone calls can be carried over a T1 line? How is the total of $1.544 \mathrm{Mbps}$ obtained for a T1 line?
Define fractional $T 1$.
Define point of presence.
What is the purpose of a CSU/DSU?
Describe how packet switching works. What is statistical concentration?
Explain the operation of a frame relay network. What technique does it use to increase data throughput and why is this a viable approach?
What is ATM and how are data moved quickly with this technique?
Compare the logic and physical configurations of SS7 and integrated services digital network (ISDN). Relate your answer to "in-band" and "out-of-band" signaling.
Which layers of the open systems interconnection (OSI) model are used by ISDN?
Which layers of the OSI model are used by SS7?
43. Which layer of the OSI model communicates directly with the four other layers? What are the other four layers?
Name and describe five types of ISUP messages.
What type of test equipment is commonly used for troubleshooting SS7 networks?
What is an OPC (origination point code)?
What is a DPC (destination point code)?
What is a CIC (circuit identification code)?
How many different reasons are there for sending an REL message? What is the most common reason?