IP SoftPhone requirements

An IP SoftPhone is a software PC that simulates a telephone (Road Warrior configuration). The VoIP perceived audio/voice quality at the PC endpoint is a function of at least four factors:

• Transducer Quality. The quality of the speaker and microphone or headset has an impact on the reproduction of the sound.
• Sound Card Quality. Several parameters affect sound card quality, the most important of which is whether or not the sound card supports full-duplex operation.
• End-to-End Delay. A PC can be a major component of delay in a conversation. PC delay consists of the jitter buffer and sound system delays, as well as the number of other processes running and the speed of the server.
• Speech Breakup. Speech breakup may be the result of a number of factors: network jitter in excess of the jitter buffer size, loss of packets (due to excessive delay, etc.), aggressiveness of silence suppression, and performance bottlenecks in the PC. Lower speed PCs and those with slow hard drives may be unable to support quality sound playback and recording, which results in breaks in received or transmitted audio. When this happens, increase the server speed, increase the amount of RAM, and reduce the number of applications competing for server or hard drive resources. One notable resource consumer is the Microsoft� Find Fast program that periodically re-indexes the hard drive and consumes significant PC resources.