将当前通话重新转移到ROUTING阶段，重新去Dialplan中进行路由。
参见：https://developer.signalwire.com/freeswitch/FreeSWITCH-Explained/Modules/mod-dptools/6586616
transfer <destination_number> [<dialplan> [<context>]]<destination_number>: 目标字符串。[<dialplan> [<context>]]:
拨号计划以及拨号计划上下文。<action application="transfer" data="500"/>
<extension name="public_extensions">
<condition field="destination_number" expression="^(10[01][0-9])$">
<action application="transfer" data="$1 XML default"/>
</condition>
</extension>
<action application="transfer" data="-bleg 2103"/>
<action application="transfer" data="-both 2103"/><extension name="dial_user">
<condition field="destination_number" expression="^dial_user(\d+)$">
<action application="bridge" data="user/$1"/>
</condition>
</extension>session:execute("transfer", "dial_user1000")