[Kamailio-Users] CDRTool and Prepaid

[Alex Balashov]

In my experience dealing with it, it is precisely at the point where 
multiple calls are involved that using a proxy for rating and mediation 
purely becomes an impossible headache.

The conclusion I always came to in my implementations, which too always 
started out with the noble goal of dealing with it all in proxy, is that 
to properly handle this, I would need to extend the functionality to 
include a B2BUA through which the calls are run that can sit there and 
monitor them at a relatively low interval and record updates to their 
duration into the database.

The B2BUA would need some sort of call control API, like Asterisk's 
Manager API, or whatever Yate has, so that an outside process can sit 
there and do statekeeping on the calls.  You could do this without 
handling media by using the B2BUA in a purely signaling capacity, which 
I think is how Yate functions by default, and how Asterisk can function 
with the "directrtpsetup" option in sip.conf.

It is then possible to know in reasonably real time the call duration 
without waiting for an accounting stop event and thus make the 
determination of whether another call should be allowed given the 
balance depletion.

-- Alex

Adrian Georgescu wrote:

> The problem with concurrent prepaid calls and single balance is that  
> you have to correlate between the call control and rating angine  
> somehow so that all calls terminate when balnce becomes zero. The  
> problem is a bit complex:
> 
> Example:
> 
> Balance = 10.
> A call starts to destination XXX, for the sake of example max session  
> time = 2 minutes
> After one minute, you start second call to destination YYY which has a  
> different price and your balance is not anymore 10 but depends on the  
> duration of the first call which is in progress.
> 
> What is the maximum session time for it given that the first call is  
> already in progress?
> What should happen with the first call?
> 
> I am looking for suggestions on implementing a proper algorithm to  
> deal with this situation in the rating engine. If you have any I would  
> be glad to hear it.
> 
> Adrian
> 
> 
> 
> 
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-- 
Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
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