Asterisk VoIP Stress Test System

I need an Asterisk-based system to stress test VoIP phone systems by handling 100-500 simultaneous calls. Requirements: – Capacity testing focus – Simultaneous call handling: 100-500 – VoIP systems preferred… (Budget: £250 – £750 GBP, Jobs: Asterisk PBX, Linux, Network Engineering, Network Security, Telecom, Telecommunications Engineering, Testing / QA, VoIP)