Now backup and edit a new blank sip.conf, just like you did with extensions.conf.
Then add the following to your sip.conf file:
[general] context=default  type=friend context=from-internal host=dynamic secret=unsecurepassword disallow=all allow=ulaw
Basic configuration will be explained in more detail in other sections of the wiki. For this example to work, just make sure you have everything exactly as written above. Even For the sake of terminology, it is useful to note that though we have this SIP configuration configured with "type=friend", most people refer to this as configuring a SIP peer.