[Asterisk-Dev] libpri ISDN features

[Steve Underwood]

Andrew Kohlsmith wrote:

>On November 24, 2004 03:36 pm, Aaron S. Joyner wrote:
>  
>
>>If you register with the ITU's website, you can obtain 3 free ITU
>>specifications at no charge.  I discovered this when I was looking for
>>exactly the same Q.931 spec.  Since the registration is pretty painless,
>>it's a good way to acquire a free copy of the spec for educational /
>>open source use.
>>    
>>
>
>I found the ITU's documents completely and totally worthless.  There was *no* 
>actual protocol layout, just highlevel hand-waving in all the documents I 
>downloaded.
>
>I found MUCH better info (along with bit-level descriptons) on the CAPI 
>website.
>  
>
Q.921 fully specifies the link protocol.
Q.931 fully specifies the messages, and the call states that relate to them.

How useless is that? :-\ What they don't tell you is whether any of 
these messages, or fields within messages, will actually exist in any 
particular network. You need to look at consult ETSI, or national 
documents to find out about that.

Regards,
Steve