install asterisk
aptitude install asterisk
edit /etc/asterisk/sip.conf
[general] context = default bindport = 5060 bindaddr = 0.0.0.0 tcpbindaddr = 0.0.0.0 tcpenable = yes [1001] type = friend callerid = User 1001 <1001> secret = 1001 host = dynamic canreinvite = no dtmfmode = rfc2833 mailbox = 1001 disallow = all allow = ulaw transport = udp [1002] type = friend callerid = User 1002 <1002> secret = 1002 host = dynamic canreinvite = no dtmfmode = rfc2833 mailbox = 1002 disallow = all allow = ulaw transport = udp
edit /etc/asterisk/extensions.conf
[general] static=yes writeprotect=no [default] exten => 1001,1,Answer() exten => 1001,n,Dial(SIP/1001,20,tr) exten => 1001,n,Hangup exten => 1002,1,Answer() exten => 1002,n,Dial(SIP/1002,20,tr) exten => 1002,n,Hangup.