[asterisk-users] Friend/user/peer in plain English?

[Gilles]

Hello

	I've done some googling, but still puzzled at my working
configuration.

Apparently, a "user" can only receive calls through Asterisk, a "peer"
can only make calls, and a "friend" can do both.

If that's correct, I don't understand why my VOSP requires the
following settings in sip.conf to let my Asterisk server make/receive
calls to/from the PSTN:

=============
[general]
...
register => me:pass at vosp.com

[vosp_outgoing]
type=peer
host=vosp.com
username=me
secret=pass
fromuser=me
fromdomain=vosp.com
nat=yes
canreinvite=no
qualify=yes

[vosp_incoming]
;why not type=user?
type=peer
host=vosp.com
context=from_vosp
nat=yes
canreinvite=no
insecure=port,invite
qualify=yes

[6011]
type=friend
secret=pass
context=my-phones
host=dynamic
qualify=yes
nat=no
=============

I would expect [vosp_outgoing] to be of type=peer, while
[vosp_incoming] should be type=user.

As a side-note, why do we need both a "register" and "fromuser/secret"
to make calls through a VOSP?

Thanks for any hint.