[transport-local]
type = transport
protocol = udp
bind = 127.0.0.1

[transport-private-udp]
type = transport
protocol = udp
bind = 10.70.1.33

[transport-public-udp]
type = transport
protocol = udp
bind = 212.XXX.XXX.87

All endpoints are defined like this:-

[companyname_206]
type=endpoint
context=companyname_phones
disallow=all
allow=alaw
direct_media=no
named_pickup_group=companyname
named_call_group=companyname
mailboxes=6@companyname
moh_suggest=default
media_use_received_transport=yes
accountcode=companyname
force_rport=yes
rtp_symmetric=yes
rewrite_contact=yes
auth=auth_companyname_206
aors=companyname_206

[auth_companyname_206]
type=auth
auth_type=userpass
password=SECRET
username=companyname_206

[companyname_206]
type=aor
max_contacts=1
qualify_frequency=60
qualify_timeout=10000
minimum_expiration=300
remove_existing=yes