VoIP Voice and Fax Signal Processing

13.6 BULK CALLS FOR STRESS TESTING

VoIP voice solutions need to be stress tested to observe how they are performing over time. The voice call stress tests are conducted with or without the presence of data traffic and other applications running on the gateway. Multiple voice calls are established within the gateway or from a third-party reference gateway. To make multiple voice calls, BCGs are used. Bulk call generators apart from making multiple voice calls also measure the voice quality in the call using PSQM, PESQ, and other statistics like signal-to-noise ration (SNR), one-way delay, and round-trip delay. These stress tests with bulk call generators are performed for different types of supported codecs such as G.711, G.729, and G.723.1. A BCG will not know which codec is used. Different packetization periods are also used for stress tests with BCGs. The most popularly used BCGs are from Spirent, Ameritec, Teltone, and Sage Instruments. The details on these instruments are available at the respective manufacturer's website. Spirent offers bulk call generators through its product series Abacus. Abacus II is the most current version. This equipment comes with at least two telephone interfaces up to several T3/E3 span interfaces. These instruments also give several call details and various statistics of the voice quality. Ameritec BCGs are also popularly used for stress testing of VoIP voice calls. Ameritec BCGs also give precise impairment measurement, and they calculate MOS values. ...