[asterisk-users] SIP carrier billing technicalities

[Alex Balashov]

Robert McNaught wrote:
> Hi,
> 
> Does anyone know anything about the following?
> 
> In a hosted environment where several area DIDs are provisioned on a
> single server, how do most carriers establish the origination DID,
> number.
> 
> Asterisk allows us to modify the CallerID, name, number and DNID
> channel variables before dialling out via SIP.  Most carriers will
> allow us to spoof a callerID when placing a call, and pass it forward.
>  We can also spoof the DNID also before the call is placed, although I
> am not sure this is carried forward to the outgoing proxy, using SIP.
> 
> Do most carriers the carrier just use CallerID as an origination
> number?  As far as I am aware, the concept of a BTN is gone with
> SIP....
> 
> Does this mean its possible to save money on your bill, by modifying
> CallerID so that the origination number is seen to be a local call?

This depends on whether the billing arrangement is trunk billing, or 
ANI-based subscriber billing.

If it's trunk billing, it practically doesn't matter what the source and 
destination number is;  the usage charges are simply assessed based on 
(typically) the minutes consumed by voice-bearing media on the call 
signaled over the trunk.

If it's ANI or DNIS based billing, then the source and destination 
become important.  Typically on SIP trunks, which is what one gets from 
carriers, that is not how it is done, however.  The caller ID and such 
hold a relatively cosmetic meaning in trunk billing.


-- 
Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
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