SIP.conf
==================================================
[provider-inbound] ;(exact format/casing required)
type=friend
host=provider.net
context=inbound ;(ext-did or from-trunk for A@H)
username=username
secret=secret
allow=all
insecure=very
canreinvite=no

[provider-outbound] ;(exact format/casing required)
type=friend
host=provider.net
context=inbound ;(ext-did or from-trunk for A@H)
username=username
fromuser=username
trustrpid=yes
sendrpid=yes
secret=secret
allow=all
canreinvite=no

[homephone]
type=friend
secret=secret
qualify=yes
nat=no
host=dynamic
canreinvite=no
context=default

extensions.conf
=============================

[outbound]
exten => _1NXXNXXXXXX,1,Dial(SIP/${EXTEN}@provider-outbound)
exten => _011.,1,Dial(SIP/${EXTEN}@provider-outbound)


exten => _911,1,Dial(SIP/911@provider-outbound)

[inbound]
exten => <mynumber>,1,Dial(SIP/homephone)