Internet Telephony Lecture Notes

24 June 2008 • Quality of Service

Outline

Quality

• Two principle quality factors are distortion and delay.

  • How long does it take for the listener to hear the speaker?

  • What does the listener hear compared to what the speaker says?

• PSTN quality has been massivly studied and standardized.

PSTN Quality

• PSTN quality has been massivly studied and standardized.

  • ITU G.114 delay standards; G.131 echo control.

Internet Quality

• Internet quality has been less studied and agreed upon.