Something

Sip.conf

[from-internal]

exten => _*26.,1,Dial(SIP/${EXTEN:3}@localhost)
exten => _*26.,1,Congestion
exten => _*26.,102,Busy
<technology></dialstring>
SIP/<exten>@<10.69.69.20>:<portno>


Extension.conf


[general]

port = 5060           ; Port to bind to (SIP is 5060)
bindaddr = 0.0.0.0    ; Address to bind to (all addresses on machine)
disallow=all
allow=ulaw
allow=alaw
context = from-internal ; Send unknown SIP callers to this context
callerid = Unknown