一、返回480
Reason: Q.850;cause=96;text="MANDATORY_IE_MISSING"
我这里遇到原因是：fs外呼时， 对端的ip端口写错了。freeswitch internal端口是5060，external端口是5080
<extension name="Output fs"><condition field="destination_number" expression="^0(10[01][0-9])$"><action application="bridge" data="sofia/external/sip:$1@10.10.10.10:5080"/></condition></extension>二、返回503