asterisk users - Oct 2011 - BT line: unavailable vs withheld numbers?

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.

-- 
AJS

Answers come *after* questions.

AJ,

Banging my head other a similar problem here in US.

What I know so far the callerid function produces the following bitmap flag:

 1. CID Private Name
 2. CID Private Number
 3. CID Unknown Name
 4. CID Unknown Number
 5. CID Message Waiting
 6. CID No Message Waiting

For example, Flag=3 means Private Name and Number.

If a Number and / or a Name are blocked for whatever reason a Null value
is written to the respective returned parameter.

What I do not know is how to analyze the flag in a dialplan.

The problem with analyzing a Null value as you mentioned in your message
is with multiple source causes:

  * CID recognition failure
  * CID unknown
  * CID blocked

-Vladimir



On 10/11/2011 6:16 AM, A J Stiles wrote:
> 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.
>
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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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