[Users] Accounting Information and Call Transfers

[Bogdan-Andrei Iancu]

Günther Starnberger wrote:

>On Wed, 2005-07-06 at 12:16 +0300, Bogdan-Andrei Iancu wrote:
>
>Hello,
>
>  
>
>>Indeed, accounting the transferred calls may be trick.
>>A short idea that might help you:
>>    - spy the REFER request and add to the "Refer-to" header's URI a 
>>parameter containing the billing user (usually is FROM URI of the REFER) 
>>- use avpops to do this -> avp_write() to get the from URI into an AVP 
>>and subst() to added the AVP as a Refer-to URI parameter (for example 
>>named "billing".
>>    - look for INVITEs which have in RURI, URI with the "billing" 
>>parameter; if so, move its value  to the X-Account header; For this you 
>>need the new avp_subst() function (only in OpenSER 0.10.x)-> the idea 
>>will be like this: move RURI in an AVP (avp_write), extract from the avp 
>>only the param (avp_subst) and push the avp as header (avp_pushto).
>>    
>>
>
>Thanks for the info - I already thought of something similar, but the
>downside of this solution is that i would need some kind of
>'ticket' (e.g. a random number) which i put into the refer-to header -
>otherwise the remote peer would be able to call on someone elses credit
>even without a transfer.
>  
>

yes, this is a strong point

>Something like the following steps:
>* OpenSER gets a REFER and writes a random number together with a
>timeout value in the database.
>* OpenSER puts this number in the Refer-to header as a parameter
>* On an incoming call the number is checked against the database - if it
>matches the account of the person wo initiated the transfer is used -
>otherwise the account of the person who sent the INVITE is used.
>
>I hoped that there would be a simpler solution for this problem :(
>  
>
a way to simplify it is to relay on acc data: log the REFER with the 
FROM, REFER-to hdr (and whatever you find useful). Then, from ACC table, 
you can put thing together : A <-> B, A refer to B with refer-to C, 
B->C; so A must pai also fo B->C; checkings timestamps will avoid any 
doubts.

Maybe using some additional random tokens to re-enforce the correlation 
between the two calls will be good.

>How is this case usually handled in the VOIP world? Are calls just
>assigned to the account of the person who sent the invite? Or are
>workarounds (either your suggestion or a B2BUA which keeps track of the
>calls) common?
>  
>
I don't thing a B2BUA is really required.

regards,
bogdan