September 2008
Intermediate to advanced
550 pages
18h 10m
English
Content preview from VoIP Voice and Fax Signal Processing
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13.12 VOICE QUALITY CERTIFICATIONS
Voice quality certification is a very important action for promoting the solutions. Several focused categories for voice quality certification exist. The main are given here:
- Agencies like American Telephone and Telegraph (ATT) and British Telecom certify for echo canceller and overall listening quality. This is mainly for voice aspects and not for the complete VoIP product.
- The Telecommunication Technology Association (TTA) [www.tta.or.kr] tests [URL (TTA)] and certifies for voice and several networking functions. Usually the tests are conducted on 50 different signaling and voice operations and their parameters.
- The Tolly Group [URL (Tolly)] also conducts a certification program called the “VoIP capable infrastructure (Quality of Service),” which verifies the device under test's quality-of-service (QoS) mechanisms. It can adequately support latency-sensitive applications such as voice in a congested environment by providing sufficiently low latency as well as voice quality scores that are coincident with those deemed toll quality [www.tolly.com].
- There are some test agencies for fax over IP testing such as Commetrex Corporation [www.commetrex.com].
- CT Labs [www.ct-labs.com] also conducts several stress and voice quality tests.
The test agencies and testing support may change over time based on the time-sensitive requirements. Therefore, refer to the latest information on test agencies.
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