[asterisk-users] Unable to obtain dialed number through ZAP

[John Novack]

Jay R. Ashworth wrote:
> On Mon, Mar 24, 2008 at 07:49:31AM +0000, Gordon Henderson wrote:
>   
>> On Mon, 24 Mar 2008, mark morreny wrote:
>>     
>>> What I need to do is to try to route called based on the dialed number as I
>>> have multiple DIDs on my line.  Is this something that can be done?  Is this
>>> something to do with the hardware that I am using?  If so, what kind of
>>> hardware do I need to accomplish this task?
>>>       
>> Based on this and your other posts, I'd suggest that it's not possible with your setup. Telephnoe companies don't normally send the called phnoe number down analogue lines, just the calling number (and even if they did,I'm not sure asterisk has a means to extract it)
>>     
>
> You're talking about DNIS: Dialled Number Identification Service. 
>
> Some telcos can provide it on some analog services, usually those
> described as DID, terminated on Dialogic DID-120 cards, and sold to
> answering services run by little old ladies with 4-digit nixie tube
> display boxes on the shelf next to the WeCO 300 (and no, to coin a
> phrase, I am *not* making this up).
>
> IOW: Yeah, go get ISDN.
>
> Cheers,
> -- jra
>   
DID = Direct Inward Dialing
In the telephone world, DID has been available for many years. 
Originally as a specialized trunk or set of trunks, where the PBX or 
remote end supplied battery towards the CO, and the CO outplused the 
last number of digits to the PBX, depending on the size of the PBX this 
could have been 3 or more digits. Later DTMF. What you would call an 
analog connection.
With proper coding Asterisk SHOULD be able to handle DID trunks with FXS 
circuits.
Asterisk can PROVIDE DID access to a PBX via FXO circuits, assuming the 
PBX can be programmed for no wink.
Answering services did use devices to decode and display the digits ( 
Nixie or LED ) so they would know how to answer the line, often on a 1A2 
key set. This has evolved in later years to more automated systems.

Somewhere along the line, DID has become misused. What many call DID is 
LDN, or Listed Directory Number. LDN is usually the Line Number, though 
not all lines have numbers. Many telcos provide a group of lines or 
trunks under one number with multiple appearances in a hunt group, often 
tarriffed at a different rate.

Probably more than anyone wanted to know about Direct Inward Dialing

John Novack


-- 
Dog is my co-pilot