I have  kamailio server and a freeswitch server during a call the kamailio passes the call to freeswitch to play a media and back to kamailio for routing to the destination, this works fine however for samsung devices (any ROM using linphone).  On other device brands, it does not work it always returns USER_BUSY or NUMBER_NOT_FOUND.  After investigation, I found out that if the transport is UDP then it works on all phones, the problem happens if I use TCP as the transport.  Anyone had experienced on this?

Thanks,

Jason