Hi, I have an FS server running on an AWS instance and it does not call between mobiles connected to the same WiFi. The call is successful if each of the mobiles is connected to different Wifi or by mobile network (4G). Obviously FS is always in a different network and I use a domain/URL to routing the calls. I also do not see anything strange in the logs. I think that call does not occur because the server does not find the destination number as registered and hangup/abandoned the call by timeout. It always works except when the two mobiles are connected to the same wifi. My current configuration is the next: vars.xml: <X-PRE-PROCESS cmd="set" data="bind_server_ip=auto"/> <X-PRE-PROCESS cmd="set" data="external_rtp_ip=host:mydomain.us"/> <X-PRE-PROCESS cmd="set" data="external_sip_ip=host:mydomain.us"/> <!-- Internal SIP Profile --> <X-PRE-PROCESS cmd="set" data="internal_auth_calls=true"/> <X-PRE-PROCESS cmd="set" data="internal_sip_port=5060"/> <X-PRE-PROCESS cmd="set" data="internal_tls_port=5061"/> <X-PRE-PROCESS cmd="set" data="internal_ssl_enable=false"/> <!-- External SIP Profile --> <X-PRE-PROCESS cmd="set" data="external_auth_calls=false"/> <X-PRE-PROCESS cmd="set" data="external_sip_port=5080"/> <X-PRE-PROCESS cmd="set" data="external_tls_port=5081"/> <X-PRE-PROCESS cmd="set" data="external_ssl_enable=false"/> internal.xml: <param name="apply-nat-acl" value="rfc1918.auto"/> <param name="local-network-acl" value="rfc1918.auto"/> <param name="ext-rtp-ip" value="autonat:$${external_rtp_ip}"/> <param name="ext-sip-ip" value="autonat:$${external_sip_ip}"/> internal-ipv6.xml: <!-- Shouldn't set these on IPv6 --> <!-- <param name="ext-rtp-ip" value="$${external_rtp_ip}"/> --> <!-- <param name="ext-sip-ip" value="$${external_sip_ip}"/> --> external.xml: <param name="local-network-acl" value="rfc1918.auto"/> <param name="ext-rtp-ip" value="autonat:$${external_rtp_ip}"/> <param name="ext-sip-ip" value="autonat:$${external_sip_ip}"/> external-ipv6.xml: <param name="local-network-acl" value="rfc1918.auto"/> <!-- Shouldn't set these on IPv6 --> <!--<param name="ext-rtp-ip" value="auto-nat"/>--> <!--<param name="ext-sip-ip" value="auto-nat"/>--> One call example is "sip:1009@mydomain.us:5080"