[asterisk-users] BT line: unavailable vs withheld numbers?

[Phil Reynolds]

Quoting A J Stiles <asterisk_list at earthshod.co.uk>:

> On a BT line, how do I determine whether the number on an incoming call has
> been deliberately withheld  (by dialling 141)  or is merely  
> unavailable  (e.g.
> because it originated from overseas or passed through some ancient switching
> equipment)  ?
>
> In the first case, I want the caller to be played a message to the  
> effect that
> we are not at home to anonymous cowards but if their business is important,
> they may redial without withholding their number.  In the second case, the
> call needs to be treated as legitimate since it is not really the caller's
> fault that their number is not available.
>
> Software is Asterisk 1.8.5.0 with DAHDI 2.4.1.2.  Hardware is  
> TDM410P with two
> each FXO and FXS modules.

Assuming caller ID works reliably for you - it's not been so for me  
since I got an AEX410 - the CALLERID(name) will provide the  
information. On withheld calls, it may be blank or the word "WITHHELD"  
or even the CALLERID(num) could be "Withheld". The CALLERID(name) is  
"UNAVAILABLE" where equipment age or similar affects the situation,  
and "INTERNATIONAL" for calls from overseas.

It also gets set to "RINGBACK" for ringbacks, of course.

-- 
Phil Reynolds
mail: phil-asterisk at tinsleyviaduct.com

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