[SR-Users] NAT, TLS and location table

Hi, I am using TLS and recognize the following problem: The TLS connection are build up successfully but the natping (natping_interval = 10) does not send small dummy packets to the phones. The phones are behind a firewall with NAT. Registered phones with NAT but UDP do work correctly. They are getting the natping every 10 seconds. After 120 seconds (should be the tcp_connection_timeout) kamailio does send a FIN to the TLS phone to close the TLS connection. Should I increase the tcp_connection_timeout to a value bigger than the registration timeout? I thought I do not need that, because of the natping_interval. Is it maybe better to use a SIP-Options Ping instead of the small dummy packets? I would prefer the dummy packets because they are much smaller. BTW: Kamailio 3.1.1 and snom360 with latest v8 firmware. Thanks in advance! Best regards, Bernhard