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LOAD GENERATOR
FOR TELEPHONY BENCHMARK
SR20 SERVICE sells and rent telephony hardware solutions (call injectors) in order to benchmark call center, IVR services, etc.
A CALL INJECTOR TO BENCHMARK YOUR TELEPHONY
Load testing focus on many differents objectives, main advantage for all cases is to capitalize knowledge.
Should this knowledge be used for choosing a new brand solution or to anticipate overloads and refine corrective procedures for running production.
Check out our White Paper: testing telephony networks (White Paper).
TEST TYPES AND MEASUREMENT
 Sizing validation test: Objective is to validate accuracy of  system sizing to handle a specified volume of traffic. Volume of simultaneous calls is delivered to the system consistant with service estimates. After a call ends, new call is established in order to maintain equal level of trafic.
Hard limit test: Objective is to determine the upper bound for traffic. Pushing off this limit will disturb connected calls and new incomming calls will not be answered. This test could be oriented in 2 directions:
- If physical ressources are limited (i.e. Timeslot for a T1), the hard limit will be determine using all available resources.
- If physical ressources are not limited (i.e. VOIP calls) the hard limit will be determined by the maximum number of call that could be connected.
Long run test: The objective of this test is to detect issues that will increase downtime in production. Load at 60 to 80% of sizing validation test will run for a long time from 12 to 48h
Stress test: This methode will « shake » all components in order to determine the maximum load a system could handle. The call rate (connect / clear) per second will figure out this level.
MEASUREMENT AND RELIABILITY OF RESULTS
Measurement for a benchmark are taken for the diferent levels involved in a communication.
Network: Figures at this level give idea of network time, each message at network level is followed by an answer, delta time between these messages gave mimimum basement for communication capabilities.
MiddleWare: Network data are processed at this level by a switching engine dedicated to run an action in response to a message. Performance measurement for middleware is delta time between network message and result produced.
Application: application delay match the response time beween a query and answer as seen by end user.
Media: Media processing is more difficult to evaluate because it concern human perception of voice quality. Main media issue is to chain audio blocks smoothly.
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