[Asterisk-Users] Newbie's doubt on sip.conf

[Andrew Thompson]

kaiduan xie wrote:
> 1) Can I have two or more SIP phones acting as
> extensions in one Asterisk box, and at the same time, registered to a
> SIP proxy, say Free World Dialup? If yes, how? 

Your phone would have to support registering with more than one sip server.
It may seem like what you want, but I doubt it is necessary.

> 2) Why we need a section in the sip.conf for the
> proxy, say, Free World Dialup's fwd.pulver.com? In the
> case of 1), how to assign the value to section [fwd.pulver.com],
> since there are more than one sip phone, each with different FWD
> number?  

You should be able to register and listen for calls from multiple fwd
numbers and direct them to different extensions.

> 3) Can anyone explain the meaning of "peer", "friend",
> "user" in more details? For each case, what is the
> role of Asterisk in SIP world, a UA, a proxy, or
> others?

Peer: A connection that sends calls to asterisk.
User: A connection that asterisk sends calls out to.
Friend: an attempt at a combination of both, to simplify set up of phones
that send and receive calls. (There are several people here who will tell
you friend is evil.)

> 4) If we only use SIP phone as extensions in Asterisk,
> the SIP phone doesnot associate with outside proxy,
> does Asterisk act as a proxy for inter-extension call
> between the SIP phones? In this case, for the outgoing
>  call originating from SIP phone to other network,
> say, PSTN, does Asterisk act as a gateway? (PSTN
> connection with Asterisk is assumed.)

Hmm, let me give brief examples of things you can do(* = asterisk): 
sip phone -> * -> sip phone
sip phone -> * -> hardline adapter -> PSTN or T1/E1/BRI/etc.
sip phone -> * -> other voip service(fwd, iaxtel, etc)
sip phone -> * -> other voip service(voicepulse, nufone, iconnecthere) ->
PSTN

Most(if not all) of these can be turned around so that they are still valid
reading right to left.

-----
Andrew Thompson
http://aktzero.com/
http://www.retirequickly.com/43653