Stephane M wrote:

> Hi,
>
> I just wonder if a communication is really secure ?
>
> I mean, suppose that 2 peoplse connected to their own ASTERISK server,
> and 2 users are connected to this server...
>
> What do you think about the link between the phone and the server ?
> (Usually using SIP protocol)

There's SRTP. It would need to be explicitly supported by the handsets, and
you'll probably have to re-compile Asterisk with libsrtp support:

http://www.e164.org/wiki/AsteriskSRTP

which looks "fun":

http://bugs.digium.com/view.php?id=5413

It's not entirely clear, however, that the plaintext SIP bit is encrypted -
so whilst your voice [RTP] will be encrypted, your signalling may not be.

> - Is that easy to intercept communications ?

It Depends. Are the people spying on you on your LAN? Does your VoIP traffic
go out over the public internet?

> - Is there a way to encrypt SIP communications ? if so, how can we do that

If your calls are traversing the internet, you'd probably find it easiest to
use a VPN tunnel.

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Yes. I'm just guessing.