[asterisk-users] question on call setup

[Jerry Geis]

If I have an asterisk server and lets say 150 asterisk clients all 
running SIP
and I wish to initiate a one way call out and bring those 150 units into 
a one
way conference/ intercom group/ something ...

What is the fastest method?
how long would that call setup take before I can start talking?
Is there anything else I'm not thinking of?

Thanks,

Jerry