There is a scenario:
 
1. There is a conference with lines A, B (cisco terminals) and C (CTI port controlled by application).
2. Line A make transfer to external line D.
3. Via JTAPI test tools trying to disconnect connection D, result:
 

<pre class="code-java" style="margin: 0px; padding: 0px; font-family: monospace; font-size: 1.2em; color: #333333; line-height: 13px; text-align: left;"><pre class="code-java" style="margin: 0px; padding: 0px; font-family: monospace; font-size: 1.2em; color: #333333;">com.cisco.jtapi.InvalidStateExceptionImpl: Operation not allowed
at com.cisco.jtapi.ConnectionImpl.disconnect(ConnectionImpl.java:701)</pre>
</pre>
<pre class="code-java" style="margin: 0px; padding: 0px; font-family: monospace; font-size: 1.2em; color: #333333; line-height: 13px; text-align: left;">4. Line B disconnects from conference.</pre>
<pre class="code-java" style="margin: 0px; padding: 0px; font-family: monospace; font-size: 1.2em; color: #333333; line-height: 13px; text-align: left;">5. Via JTAPI test tools trying to disconnect connection D - connection successfully disconnects.</pre>
<pre class="code-java" style="margin: 0px; padding: 0px; font-family: monospace; font-size: 1.2em; color: #333333; line-height: 13px; text-align: left;">
</pre>
<pre class="code-java" style="margin: 0px; padding: 0px; font-family: monospace; font-size: 1.2em; color: #333333; line-height: 13px; text-align: left;">Any suggections about why operation not allowed?</pre>