Like to test more than 4 concurrent call to one asterisk box, how to configure it from freepbx

I like to check the performance of my asterisk box, the simple one is through the load testing, but I only have one DID, here it is my question.

  1. can I use one DID to support 4 concurrent call, if can, how to configure it.

  2. if can not, what may be the limitation of the concurrent call one DID can support, and how to set up multiple DID on one asterisk box.

    All of the setting are refer to SIP trunk, I have no card.

A DID is just a number used to connect to the system but it identifies itself to the system as a call on line xxxx. More important is how is that DID being delivered and the channel limits of that connection? A T1/E1/PRI, SIP and IAX can multiple channels so if you have enough channels via that method (sip in your case) to support multiple concurrent connections, you can just use the same phone number over and over until you have used all the channels up by your connection method.