618 Chapter 16: Voice Techniques
As you know, communication among humans is quite different from communication among
computers. When delay is introduced to data traffic, the packet can be retransmitted. A protocol
ensures that the packet is placed in the proper sequential order and that the data is delivered.
When delay is introduced to voice traffic, the packet cannot be retransmitted. If a voice packet
is retransmitted, this will only confuse the listener, because the user expects to hear
conversation in real time. Unexpected pauses will puzzle the listener.
Poorly Tuned Voice Network
Under perfect conditions, there are problems with understanding and interpreting what is said.
Imagine how communications might suffer on a poorly tuned voice network. Here is an
example. At Acme Law, a lawyer is calling a client about a pending divorce case. The network
does not have QoS for voice. Here is an excerpt from the conversation:
Lawyer: What are the grounds for your divorce?
Client: A home located on about two acres near the county line.
Lawyer: No, what is the foundation for your case?
Client: It is made of concrete, brick, and mortar.
Lawyer: Do you have a grudge?
Client: No. We have a two-car carport and have never really needed one.
Lawyer: Is there any infidelity in your marriage?
Client: Yes. Both my son and daughter have stereo sets in need of replacement.
Lawyer: Have you ever beat your wife up?
Client: Yes. About twice a week I get up earlier than she does--although on the weekends she
usually beats me up.
Lawyer: Why does your wife want a divorce?
Client: Who knows? Ever since I got this new voice over data network, she thinks I have a
problem communicating.
Handling delay is caused by all the components that must handle the voice traffic during its
transmission. In a typical voice-over-data network, the following components might handle the
signal in some way, thereby adding to the delay time:
·
Packetization and depacketization of voice traffic
·
Queuing of packetized voice
·
Coding and decoding of digital voice signals
87200333.book Page 618 Wednesday, August 22, 2001 1:41 PM