Influence of Security Mechanisms on the Quality of Service of VoIP

While Voice over IP (VoIP) is advancing rapidly in the telecommunications market, the interest to protect the data transmitted by this new service is also rising. However, in contrast to other internet services such as email or HTTP, VoIP is real-time media, and therefore must meet a special requirement referred to as Quality-of-Service to provide a comfortable flow of speech. Speech quality is worsened when transmitted over the network due to delays in transmission or loss of packets. Often, voice quality is at a level that even prevents comprehensive dialog. Therefore, an administrator who is to setup a VoIP infrastructure might consider avoiding additional decreases in voice quality resulting from security mechanisms, and might leave internet telephony unprotected as a result. The inspiration for this paper is to illustrate that security mechanisms have negligible impact on speech quality and should in fact be encouraged.