Change SIP domain

Appologies for the simple nature of this query, we are new to Asterix. Our installation is working fine and we can make both incoming and outgoing calls between sip devices, soft and hard phones. My query is when we make a call, the person receiving the call it comes up as say 3001@ - extension@publicipaddress

How do I change the configuration so the public ip address is the sip domain name instead.

Thank you in advance on anyones help.


Please provide the configuration you are currently using.