Creating two asterisk boxes for load testing

Hello, I have been researching this for a long time, and all i end up doing is confusing myself more and more.

What i need to do is to create a new asterisk box which is capable of load testing an already set up asterisk box. This needs to be done through the local network, so there are no costs involved. A PHP interface is preferred, but not necessary.

I am extremely new to this, and have been thrown into the deep end it seems! Any help you can give me would be great.

Thanks
Elliot