The protocol is SIP. The profiles relevant for the incoming call test with echo are here: Dialplan: ********* <!-- http://wiki.freeswitch.org/wiki/Dialplan_XML --> <include> <context name="public"> <extension name="From_Asterisk"> <condition field="destination_number" expression="^(K00003333100004444\d{3})$"> <action application="answer"/> <action application="echo"/> </condition> </extension> </context> </include> Sip Profiles: ************* <!-- http://wiki.freeswitch.org/wiki/Sofia_Configuration_Files --> <profile name="external"> <!-- This profile is only for outbound registrations to providers --> <gateways> <X-PRE-PROCESS cmd="include" data="external/*.xml"/> </gateways> <aliases> <alias name="outbound"/> </aliases> <domains> <domain name="$${domain}" parse="true"/> </domains> <settings> <param name="debug" value="1"/> <param name="comfort-noise" value="false"/> <param name="sip-trace" value="no"/> <param name="rfc2833-pt" value="101"/> <param name="sip-port" value="5080"/> <param name="dialplan" value="XML"/> <param name="context" value="public"/> <param name="dtmf-duration" value="100"/> <param name="codec-prefs" value="$${outbound_codec_prefs}"/> (comment: using PCMA) <param name="hold-music" value="$${hold_music}"/> <param name="use-rtp-timer" value="true"/> <param name="rtp-timer-name" value="soft"/> <param name="manage-presence" value="false"/> <param name="aggressive-nat-detection" value="false"/> <param name="inbound-codec-negotiation" value="generous"/> <param name="nonce-ttl" value="60"/> <param name="auth-calls" value="false"/> <param name="rtp-timeout-sec" value="1800"/> <param name="rtp-ip" value="$${local_ip_v4}"/> <param name="sip-ip" value="$${local_ip_v4}"/> <param name="ext-rtp-ip" value="$${local_ip_v4}"/> <param name="ext-sip-ip" value="$${local_ip_v4}"/> <param name="rtp-timeout-sec" value="300"/> <param name="rtp-hold-timeout-sec" value="1800"/> <!--<param name="enable-3pcc" value="true"/>--> </settings> </profile> Gateway (one of them): ********************** <include> </gateway> <gateway name="100004444300"> <param name="username" value="100004444300"/> <param name="realm" value="10.3.1.21"/> <param name="from-user" value="100004444300"/> <param name="from-domain" value="10.3.1.21"/> <param name="password" value="XXXXXX"/> <param name="extension" value="K00003333100004444300"/> <param name="proxy" value="10.3.1.21"/> <param name="expire-seconds" value="600"/> <param name="caller-id-in-from" value="false"/> </gateway> </include>