5 Jul
2006
5 Jul
'06
10:07 a.m.
Just to expand a bit on the last messages (a good thread, BTW :-)
- A full B2BUA will be in both the signalling AND the RTP path.
Mediaproxy is only in the RTP path
- FYI: The new codebase for SEMS is a full B2BUA
- Pre-paid handling and terminating a call can basically be done in
three ways: The way described in this thread (using an external agent
that generates a "fake" BYE), a full B2BUA (often a session border
controller) that keeps both signalling and media and thus can internally
generate a BYE at will, and using the Session-Timer header (must be
supported by at least one party, i.e. the gateway) where a reINVITE is
done every x interval and the call can thus be terminated
- A fourth way has been explored by several people, but I'm not aware of
any implementations: SER can be made dialog-aware fairly simple and a
new timer module in CVS head can be used to review ongoing dialogs and
generate a BYE (the module can generate a BYE using the internal uac
functionality; also available from FIFO)
- A fifth way would be to implement a signalling-only B2BUA in ex. SEMS
(and thus avoid the dependency on media going through a central server).
You would have to have mediaproxy/rtpproxy in addition, and you wouldn't
be able to detect UAs that suddenly disappear from the call (i.e. no
RTP) unless you proxy. However, you would be able to terminate the call
based on credit.
- To Ryan: If you find you want to remove the depedency on sipsak, you
may want to look at the FIFO uac functionality. There is a ctd.sh script
in the examples dir that shows how to use it.
g-)
Ryan Pagquil wrote:
Hi Daniel,
Our setup is like what you have. We have SER /Mediaproxy, for
the missing BYE's mediaproxy 1.7.2 do the job and to terminate calls
we have a perl script that checks the radacct with zero
acctsessiontime and acctstoptime entries then compare it to the
current credit of the username and if insufficient the script sends a
BYE to both ends where the information came from radacct entry. The
perl script uses sipsak to generate BYE message.
Regards,
Ryan
At 07:31 AM 7/5/2006, Daniel Salama wrote:
Thank you for the prompt response and the
explanation.
Currently, I don't have any code in place. However, I was trying to
simplify the whole architecture. I have a SER box talking to Radius
for authentication and accounting. I'm also using Mediaproxy as a NAT
helper. Then, I have Asterisk for IVR auto attendant and voicemail.
Since Mediaproxy is going to be in the media path anyhow to help in
NAT, I just don't want to have another Asterisk server in the media
path just for the Dial command with the timeout.
What would be an elegant alternative? I know that in the ISP dial-up
world, Radius is more than capable of specifying max session time.
Wouldn't SER/Mediaproxy "understand" the Radius attribute for max
session time? I know SER doesn't stay in the media path but by being
statefull, it can "listen" to all messages between the end points,
including BYE. So, why couldn't SER/Mediaproxy "insert" a BYE message
somewhere? Maybe it could be a simple as writing a simple external
process that constantly monitors sessions time and "inserts" the BYE
message using SER's fifo, in a similar way that serctl talks to SER.
Thanks,
Daniel
On Jul 4, 2006, at 5:03 PM, sip wrote:
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All Asterisk B2BUA does, really (I'm
referring to the script, not
the Asterisk
patch itself), is authenticate a call coming in, and then lookup in
radius
what the session timeout for that call should be. It then creates
an Asterisk
dial string and sets the call timeout to be X number of seconds
based on the
session-timer attribute in radius.
If media proxy allows you to set session timers on the fly or has
some sort of
polling system (I don't know, I've never used it), allowing you to
terminate a
call after a certain period of time, then no, you wouldn't need
Asterisk B2BUA.
We actually ended up only partly using Asterisk B2BUA for our
stuff, because
it didn't quite do everything we wanted (it's really only a B2BUA
and it
relies rather heavily on some odd conventions in radius for
authentication
without a password (not really authentication)), so we coded our
own setup
which keeps track of session timeouts and call costs and the like
and then
uses the Asterisk B2BUA framework to create the Asterisk dial
string. At this
point, there's no real reason we couldn't replace the whole thing
with our own
code (it became 95% ours in the process, but the process would have
gone
NOwhere without the original code to set us in the right
direction). If you're
in a similar situation with mediaproxy, and it allows session
timers of some
sort, there's no real reason to NOT use your own setup.
N.
On Tue, 4 Jul 2006 16:51:12 -0400, Daniel Salama wrote
> After reading this forum:
>
> http://www.voipuser.org/forum_topic_4468.html
>
> it made me wonder, whether or not you really need B2BUA if you
> already have Mediaproxy in your environment. I know the purpose of
> Mediaproxy is to help with NAT situations. However, given the fact
> that Mediaproxy is always in the media path, couldn't it be ALSO
> used to "terminate" a call in progress, the same way that B2BUA
> can? And by B2BUA I refer to the Asterisk B2BUA, all within the
> context of prepaid type services.
>
> Any comments?
>
> Thanks,
> Daniel
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