Daniel, received is FreeSwitch. As wrote above Kamailio do not send any data. Kamailio just send two packets. 1) `SYN` and receive `SYN/ACK` packet; 2) `RST` packet.
Also I start kamailio without `-x tlsf` arg with same config to same FreeSwitch, then Kamailio able send MSP message to FreeSwitch.