If you are using the Asterisk PBX system, the following are your recommended settings, simply copy and paste these into your server if it's FreePBX, Trixbox, Elastix or similar
Trunk Name: bablio
Peer Details
insecure=port,invite
host=sip.bablio.com
context=default
directmedia=no
canreinvite=no
type=peer
username=**Your-User-ID**
fromuser=**Your-User-ID**
secret=**Your-PASSWORD**
qualify=no
nat=no
disallow=all
allow=gsm
allow=alaw
allow=ulaw
dtmfmode=rfc2833
USER Context: **Your-User-ID**
User Details
disallow=all
allow=gsm
allow=alaw
allow=ulaw
context=from-trunk
dtmfmod=rfc2833
host=sip.bablio.com
insecure=port,invite
directmedia=no
canreinvite=no
nat=no
type=friend
qualify=no
deny=0.0.0.0/0.0.0.0
permit=202.43.66.0/24
Registration
**Your-User-ID**:**Your-PASSWORD**@sip.bablio.com