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Dear Asterisk experts,<br>
<br>
I would like to draw your valuable attention on the following situation to
see whether some of you have encountered it before and have found solutions
/ workarounds.<br>
<br>
We want to place Asterisk behind an existing PBX (connected to the PSTN)
using an E1/PRA line.<br>
<br>
PSTN -- Telco E1 -- [existing PBX] -- E1/PRA -- [Asterisk+Digium E100P] --
SIP phones<br>
<br>
<br>
We observe the following behaviour:<br>
<ul>
<li>in the call direction "Asterisk" to "existing PBX" (SIP phone calling
out to PSTN), it works great</li>
<li>in the call direction "existing PBX" to "Asterisk" (PSTN user calling
in to SIP phone), we get the following error on the Asterisk console:</li>
</ul>
<pre wrap="">WARNING[11276]: File chan_zap.c, Line 5719 (zt_pri_error): PRI: XXX
<span class="moz-txt-citetags">> >>>></span>Missing mandatory IE 24/Channel Identification XXX
</pre>
<ul>
<li>in the call direction "existing PBX" to "Asterisk", we observe that
the Q.931 SETUP message sent by the "existing PBX" doesn't contain a channel
identification IE<br>
</li>
</ul>
We double-checked the Q.931 SETUP format on DSS1 specification and we found
that <span class="moz-txt-citetags"></span>the Channel Identification is:
"Mandatory in the network-to-user <span class="moz-txt-citetags"></span>direction.
Included in the user-to-network direction when a user wants to indicate a
channel. If not included, its absence is interpreted as <span
class="moz-txt-citetags"></span>'any channel acceptable'." (section 3.1.14,
note 4).<br>
<br>
We assume that the call direction "existing PBX" -> "Asterisk PBX" is
"user-to-network", which means that the channel identification IE is optional
in SETUP messages sent by the "existing PBX", meaning 'any channel acceptable'.<br>
<br>
(Asterisk is configured to play the NETWORK side with "signalling=pri_net"
<span class="moz-txt-citetags"></span>in zapata.conf)<br>
<br>
<br>
However, Asterisk doesn't seem to want to select a channel and return it
to the "existing PBX" in the SETUP ACK (as does a Cisco gateway in the exact
same configuration).<br>
<br>
In conclusion, it seems that the functionality to answer a call without a
given channel is not there in Asterisk and we think missing this functionality
is critical as we believe the above scenario is an important and likely usage
scenario for many people.<br>
<br>
Can someone please confirm the above observation ? <br>
If yes, does anyone (Mark ?) have plans to add that functionality into Asterisk
in the near future ?<br>
<br>
We'd be happy to help beta test it .<br>
<br>
Thank you all in advance for your answers and thank you all anyhow for the
great work you've done with Asterisk.<br>
<br>
Best regards,<br>
<br>
Nicolas Dramais - Belgium<br>
<br>
<br>
<br>
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