[asterisk-users] sip echo server

[Ali Khalfan]

 I'm trying to find a way to setup a SIP server that will mainly echo
 back a request from one agent only,

 my question is do i need to setup any of the other conf files besides
 extensions.conf and sip.conf?

 the book says "If you plan on a pure VoIP network, the only real
 requirement is the asterisk package," ,

 but i'm doubtful about zaptel.

 can anyone help me out?