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VoIP Quality Control 2007
2007-04-03
We distilled the offerings of a dozen vendors into a "not-so shortlist" of packages. These represent a good ross section of the tools available today, but they are not the only ones. Due to space and time constraints, not all vendors with applicable packages are included. These vendors offer products that address at least two of the three main operational environments:
1. Problem investigation (typically post-deployment): Troubleshooting specific problem; often entails laptop-based software and short-term, passive monitoring (watching real-user VoIP traffic) of a link or specific endpoints via a mirrored switch port.
2. Ongoing monitoring (pre- or post-deployment): Long-term continuous or permanent monitoring, often via multiple probes on dispersed links; may be inserted inline or on mirrored ports; data collected at a central server; can be passive monitoring, active generation of simulated calls, or both.
3. Simulation, base lining (typically pre-deployment): Long orshort term; simulated (synthetic) VoIP calls and other traffic are generated to assess suitability for VoIP, VoIP load capacity, testing of call controllers or other VoIP infrastructure; quality of service performance and/or SLA compliance.
A year ago we still cautioned users to make sure any VoIP analysis tool they bought supported SIP, ideally as a standard component. That is no longer necessary. All of the leading packages now support SIP integrally. It's fast becoming a SIP world, and users from now on will have an increasingly hard time finding analyzers that understand their particular vendor's proprietary protocols although Cisco SCCP (Skinny), Nortel (Unistim), and Avaya (H.323 variant) are still fairly common.
Active or passive VoIP monitoring remains a bone of contention although most of those on the table now support both capabilities. Active VoIP call-quality measurement is where simulated (or synthetic) VoIP calls are placed by, and measured between, strategically located test devices. This naturally consumes bandwidth on IP routes between these points; therefore, it is called intrusive monitoring. Ratings usually, but not always, employ one of the perceptual evaluation of speech quality (PESQ) measurements, which compare a received audio file to a reference original.
The results generally are in the form of mean opinion score (MOS) 1-to-5-scale ratings. Passive monitoring means watching and rating real-user VoIP traffic. Representative of passive call quality assessment is the Rfactor metric, known by other names and references including R value, E Model, and ITU G.107. Component criteria include loudness, noise, vocoder type, and delay. The result is a value on a 0-to-100 scale. A good-as-it-gets R-factor rating is 93, which can only be achieved with G.711 vocoding and everything else being nearly ideal. The MOS equivalent, by the way, is 4.4. Similarly, R-factor scores of 80 to 100 map to MOS scores of 4.0 to 5.0; R factors of 60 to 80 equate to MOSs of 3.0 to 4.0. And calls below an R factor of 60, or a MOS of 3.0, are generally considered unacceptable.
Both techniques have their place; however, from the many network analyses it has performed of both enterprise networks and carrier services, MierConsulting has found that active VoIP monitoring provides a generally better and more controllable, consistent, and accurate assessment of VoIP call quality than passive monitoring of real-user VoIP traffic.
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VoIP Providers List Information |
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About VoIP Providers List
VoIP Providers List services save time for companies searching both for information and interconnection partners, interested in voice minutes exchange, i.e. VoIP minutes termination and origination, as well as hardware and software trade. We provide information on interconnection services, VoIP hardware solutions and VoIP software , as well as overall situation in the VoIP industry.
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VoIP Providers Statistics |
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Providers in database: 3315
Users Online: 169
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