Asterisk on FreeBSD + ISDN BRI

[Thomas Wintergerst]

Hello Jussi,

Juha-Matti Liukkonen wrote:
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> On 28.5.2005, at 16.34, Hans Petter Selasky wrote:
> 
>> I know that Windows uses CAPI to support ISDN devices, but the  
>> problem there
>> is that only one ISDN device is allowed at a time. So can CAPI  handle 
>> more
>> than one physical device per CAPI interface (/dev/capi20) ?
> 
> 
> The CAPI specs (www.capi.org), part 2 section 8.5 (unix interface),  
> which is obviously written with Solaris in mind, says:
> 
> "COMMON-ISDN-API's device name is /dev/capi20. To allow multiple  access 
> by different UNIX processes,
> the device is realized as a clone streams device."
> 
> In the same section the CAPI_GET_PROFILE operation is defined to  return 
> a 16-bit unsigned value for number of supported controllers.  So 
> multiple clients for multiple controllers is possible, unless the  
> implementation somehow restricts it.

Small correction: The message parameter CID is divided into an NCCI, a 
PLCI and a controller part. The controller part has 8 bits, the msb 
beeing a flag for addressing a headset. That delivers 127 usable 
controllers, each with 2 or 30 B-channels. I think, that is currently 
enough for existing machines.

And the hint for a "clone device" should rather address the possiblilty 
to allow multiple applications CAPI access. The controllers themselves 
are all addressed by an application through the single device entry 
"/dev/capi20".

> 
>>> On 27.5.2005, at 17.06, Steven Looman wrote:
>>>
>>>> The ability to use CAPI with cheap cards (like in Windows for
>>>> example) sounds
>>>> great as it would be easier to write multiplatform applications.
>>>>
>>
>> I don't think that CAPI is fit for every situation. Putting things  in a
>> library on top of "isdnd" is going to be much more powerful than if  one
>> writes a dedicated CAPI-compatible telephony application?
> 
> 
> CAPI is a lower-level thing than isdnd; it is more akin to i4b layer  3. 
> It allows moving call control logic to userspace processes - but  more 
> improtantly, it is sort-of a standard. Which would potentially  mean 
> binary compatibility with some lunix apps.

Ack. Using CAPI one can use (nearly) all ISDN features. Other APIs 
mostly have some restrictions. But this flexibility also makes some 
things a little bit complicated (no example here ;-) ).

[...]

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Regards,

Thomas Wintergerst