301

Quality of Service (QoS) for voice is a critical feature for real-time Internet
communications. QoS for VoIP is also a much-abused topic, since it was used
for a long time by the defenders of the PSTN and the TDM PBX to scare users
away from VoIP. QoS is often invoked by network equipment vendors as a rea-
son to buy new network and monitoring equipment—to make the network
“VoIP ready.” Since SIP is mainly used for VoIP throughout the industry, we
will focus in this chapter on a balanced overview on Internet QoS for interac-
tive voice and provide authoritative references for further study on this topic.
A complete treatment would require a separate book. As an aid to readers
looking for sources on QoS for VoIP, a simple test to characterize the source is:

■■ Can the author(s) be reached using VoIP in the office and at home?

■■ Is the document meant to sell some network equipment?

As we will argue in this chapter, it is acceptable for VoIP QoS to be used as
an argument to sell bandwidth, since the higher speed the broadband connec-
tion is, the better VoIP will work. Also, as core Internet speed and broadband
access use is increasing, the location for QoS moves from the network to the
applications in the endpoints.

Quality of Service for Real-Time

Internet Communications

CHAPTER

18