Does any documentation exist for the following dial-plan example?

    <extension name="refer">

      <condition field="${sip_refer_to}">

                <expression><![CDATA[<sip:${destination_number}@${domain_name}>]]></expression>

      </condition>

      <condition field="${sip_refer_to}">

                <expression><![CDATA[<sip:(.*)@(.*)>]]></expression>

                <action application="set" data="refer_user=$1"/>

                <action application="set" data="refer_domain=$2"/>

                <action application="info"/>

                <action application="bridge" data="sofia/${use_profile}/${refer_user}@${refer_domain}"/>

      </condition>

    </extension>

We have a FS gateway in front of a sipXecs PBX. When calls are transferred, we hear music on hold until the call actually transfers. Then we get dead air until the new user picks up. We need the remote phone to hear ringback when calls are transferred.

Thanks,

Ken Fulmer