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IntroductionRecqual is collection of scripts using Asterisk and other Linux utilities to measure call quality on an automated basis.
How it WorksRecqual was designed to detect audio quality problems in a call path that may not be visible from the technology being used locally. Whether it's SIP, ZAP, or IAX the fact is there are many potential sources of call quality problems in just about any call being made. Often times a SIP "provider" may resell services, for example. While the delivery of IP packets to/from this provider may look excellent there may be other problems upstream that an analysis of the IP packets, path, etc may not be able to detect.
In scenarios such as this the only way to identify call quality problems is to analyze the audio itself. Regardless of method or transport being used, the goal of any telephony system is to deliver reliable, consistent call quality.
Recqual is designed to allow you to place a large number of automated calls (using Asterisk) using different call scenario files.
The key here is consistency. When Asterisk places the outbound call (and answers the inbound call) it will generate a set of tones while recording the return audio path. Once the run has finished Ecasound will run with various filters and noise gates to detect certain amounts of distortion, signal loss, etc.
Calls either pass or fail based on how much variation there is in the audio once it has been returned. Of course you can pass audio through any combination of networks - including the PSTN.
Almost any "call quality" problem(s) can be detected with this method. Whether it's one way calls, echo, dropped packets, distortion, etc ecasound should be able to isolate the problem calls. If not you can just tweak the script ;).
Only calls that fail are saved. These files can be imported into your favorite audio processing utility and/or run through Ecasound again if you'd like to tweak the process script to detect them automatically.
Recqual has been designed (and optimized) to work with SIP channels. For example, it has the ability to correlate problem calls with specific RTP endpoint IP addresses. However, due to the protocol independent nature of Asterisk you can use just about any channel type with a few simple changes.
Created by: krisk17, Last modification: Mon 09 of Feb, 2009 (07:56 UTC)
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