[asterisk-dev] Converting and Screening Connected Line Number

[Pavel Troller]

Hi!
  Since Asterisk 1.8, transfer of Connected Party Number is possible for most
channel technologies. It's a very good feature, but it has (AFAIK) a
limitation, which may reduce its usefullness.
  In large and complex networks, it's obvious to perform various number
translations/conversions according to specific network topology etc. For
example, Calling Party Number may be manipulated by adding a prefix, 
deleting some parts of the number, etc. Also, when Asterisk directly
cooperates with PSTN switches on a trusted level (i.e. like an operator
exchange), it's necessary to properly perform screening of the Calling Party
Number (for example, by searching in the allowed prefix list or by some other
rules) and either block the number and replace it with a system provided
(default) one, or let it pass through and set the Screening Indicator
accordingly (to the "User provided, verified and passed" value). It's also
necessary to setup the Presentation indicator according to the user wishes.
  For Calling Party Number, it's easy to do all these task by the dialplan
logic.
  However, for Connected Party Number, I cannot find a way to do it. It's
transferred totally out of control of the dialplan - obviously with Progress,
Alerting or Answer signals, but all these signals are transmitted after
the Dial() application has been started, so the dialplan execution is halted
and cannot participate on the number handling. Generally, exactly the same
level of processing of the Connected Party Number is necessary as for the
Calling Party Number to fully utilize this functionality. 
  I've tried to use various Dial() application features like M() to manipulate
the number using the CONNECTEDLINE function, but it didn't have the desired
effect. Maybe I did it wrong.
  Is there a recommended method, how to trigger a dialplan macro, which can 
perform these functions in a way that the calling party will receive the 
translated number/screening indicator etc. ? I've tried to google the answer
out, but I was not successful :-(.
  With regards,
    Pavel