I have a server with asterisk installed its ip is 192.168.15.2 and my kphone is also on the same box.

Sip.Conf

[kphone]
type=friend                   ; either "friend" (peer+user), "peer" or "user"
host=dynamic             ; we have a static but private IP address
callerid="kphone" <100>
dtmfmode=inband                 ; either RFC2833 or INFO for the BudgeTone
context=from-sip
disallow=all                  ; need to disallow=all before we can use allow=
allow=ulaw

In extension.conf

[from-sip]
exten=>1,1,Dial(SIP/${kphone},20,tr)