Hi folks,   I am using Kamailio with IMS, I added the configuration of the WebSocket to the kamailio.cfg  in the PCSCF to enable WebRTC clients like (JsSIP) to communicate with each other.. The registration works so far, however when I try to make peer-2-peer call between alice and bob, the caller gets a "403 error" "403 Forbidden Mohammed- Dialog not found on S-CSCF or Terminating user not suitable for unregistered services" from the S-CSCF..  I did trace on the PCSCF and I found a strange signaling behaviour. the invite is negotiated between the IMS components as follows: INVITE from   PCSCF  to SCSCF   INVITE from   PCSCF  to PCSCF PCSCF responses itself with "403 Forbidden - You must register first with a S-CSCF" SCSCF sends the response "403 Forbidden Mohammed- Dialog not found on S-CSCF or Terminating user not suitable for unregistered services"  to the PCSCF The private IP address of the PCSCF is 172.19.6.35 and of the SCSCF is 172.19.6.36. The PCSCF  has a public IP "193.175.132.235" The IMS components don't run on the same machine, PCSCF and SCSCF are listening to the port 5060. the WebSocket port of the  PCSCF  is 8000 Can anyone help me get a solution for this problem Thanks in advance  Best regards, Medo   Mohammed Al-khameri Technical University Berlin TUB