var.xml
<X-PRE-PROCESS cmd="set" data="external_sip_ip=公网IP"/>
<X-PRE-PROCESS cmd="set" data="external_rtp_ip=公网IP"/>
sip_profiles/external.xml 和 sip_profiles/internal.xml
<param name="ext-rtp-ip" value="$${external_rtp_ip}"/>
<param name="ext-sip-ip" value="$${external_sip_ip}"/>
<param name="aggressive-nat-detection" value="true"/>
<param name="NDLB-force-rport" value="true"/>