Asterisk SIP user vs peer

As of Asterisk 1.2, there is no reason to actually use 'user' entries
any more at all; you can use 'type=peer' for everything and the behavior
will be much more consistent.

All configuration options supported under 'type=user' are also
supported under 'type=peer'.

The difference between friend and peer is the same as defining _both_ a
user and peer, since that is what 'type=friend' does internally.

The only benefit of type=user is when you _want_ to match on username
regardless of IP the calls originate from. If the peer is registering to
you, you don't need it. If they are on a fixed IP, you don't need it.
'type=peer' is _never_ matched on username for incoming calls, only
matched on IP address/port number (unless you use insecure=port or higher).