asterisk users - Feb 2005 - Q: ISDN / E1-PRI - fax problems - Receiving and setting of Service Indicator (SIN) / Bearer Capability (BC) / High Level Compatibility (HLC) / Low Level Compatibility (LLC)

hi,

i have the problem that i'm not able to set and receive the Service 
Indication (SIN) from our E1-PRI and from our ericsson BP250.

The problem is, that the Bearer Capability (BC) together with the High 
Level Compatibility (HLC) and Low Level Compatibility (LLC) forms the 
Service Indicator (SIN).
The SIN is used to determine if the call is voice, fax or data. It's 
essential to set the SIN so the called party is able which device has to 
answer a call (e.g. telephone or fax)

as far as i dug into the source neither the BC nor the HLC or LLC data 
is forwarded to a dialplan variable and only the BC is decoded in libpri.

has anyone a solution for this?

is there any usable documentation on the HLC or LLC octets (bytes)?
i searched etsi and was overwhelmed with the searchresults (1531). what 
i need to modify libpri would be a table of possible values and where to 
find the HLC and LLC fields in the D-Channel.

regards
  frank

On Tue, 8 Feb 2005, Frank Sautter wrote:
> is there any usable documentation on the HLC or LLC octets (bytes)?
> i searched etsi and was overwhelmed with the searchresults (1531). what 
> i need to modify libpri would be a table of possible values and where to 
> find the HLC and LLC fields in the D-Channel.
ITU q.931 clause 4.5.17 for HLC and 4.5.19 for LLC. 
I'd expect ETSI ETS 300 403 01 to include q.931 by reference, possibly 
noting some differences.

Peter

Yeah, I also noticed that * lacks the ability to forward calls based on
the type of call, but I have no idea whether this issue has any priority
with the development team. It is probably better to ask this question on
Asterisk-Dev mailing list.


Frank Sautter wrote:
> hi,
>
> i have the problem that i'm not able to set and receive the Service
> Indication (SIN) from our E1-PRI and from our ericsson BP250.
>
> The problem is, that the Bearer Capability (BC) together with the High
> Level Compatibility (HLC) and Low Level Compatibility (LLC) forms the
> Service Indicator (SIN).
> The SIN is used to determine if the call is voice, fax or data. It's
> essential to set the SIN so the called party is able which device has
> to answer a call (e.g. telephone or fax)
>
> as far as i dug into the source neither the BC nor the HLC or LLC data
> is forwarded to a dialplan variable and only the BC is decoded in libpri.
>
> has anyone a solution for this?
>
> is there any usable documentation on the HLC or LLC octets (bytes)?
> i searched etsi and was overwhelmed with the searchresults (1531).
> what i need to modify libpri would be a table of possible values and
> where to find the HLC and LLC fields in the D-Channel.
>
> regards
>  frank
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hi,

i made a patch which allows the forwarding and the setting of the Bearer 
Capability ID during the ISDN SETUP phase.
this solves several problems (primarily faxing) with SIN (german: 
Dienstekennung) and asterisk.
http://bugs.digium.com/bug_view_page.php?bug_id=0003547

Frank Sautter wrote:
> i have the problem that i'm not able to set and receive the Service 
> Indication (SIN) from our E1-PRI and from our ericsson BP250.
regards
  frank