Scalable voip mobility intedration and deployment- P24: The term voice mobility can mean a number of different things to different people. Two words that can be quite trendy by themselves, but stuck together as if forgotten at a bus station long past the last ride of the night, the phrase rings a number of different, and at times discordant, bells. | 230 Chapter 6 measure this for the administrator on an ongoing basis the administrator is able to devote attention to other more pressing matters. Active voice quality monitoring comes in a few flavors. SIP-based schemes are capable of determining when there is a voice call. This is often used in conjunction with SIP-based admission control. With SIP calls RTP is generally used as the bearer protocol to carry the actual voice SIP-based call monitoring schemes can measure the loss and delay rates for the RTP traffic that makes up the call and report back on whether there are phones with suffering quality. In these monitoring tools call quality is measured using the standard MOS or R-value metrics as defined in Chapter 3 on voice quality. SIP-based schemes can be found in a number of different manifestations. Wireline protocol analyzers are capable of listening in on a mirror port entirely independent of the wireless network and can report on upstream loss. Downstream loss however cannot be detected by these wireline mechanisms. Wireless networks themselves may offer built-in voice monitoring tools. These leverage the SIP-tracking functions already used for firewalling and admission control and report on the quality both measured by uplink and downlink loss. Purely wireless monitoring tools that monitor voice quality can also be employed. Either located as software on a laptop or integrated into overlay wireless monitoring systems these detect the voice quality using over-the-air packet analysis. They infer the uplink and downlink loss rates of the clients and use this to build out the expected voice quality. Depending on the particular vendor these tools can be thrown off when presented with WPA- and WPA2-encrypted voice traffic although that can sometimes be worked around. Voice call quality may also be monitored by measurements reported by the client or other endpoint. RTCP the RTP Control Protocol may be transmitted by the endpoints. RTCP is able to encode .
