Hallo, I am sorry I write in English. I use F!B 7170 over NAT well and I can call with it a can receive calls using public VoIP services - this is OK (sipgate.co.uk ...). F!B can be called directly too if you call a SIP URI "[email protected]_of_the_fritzbox" if the modem is connected with DSL to internet and has a public IP. You can also call the F!B directly if you give it over NAT and forward SIP port 5060 and some RTP ports 16384-16482 from the essential router. But now, I get a state when I cannot forward the 5060 port at the essential router but I can forward an other SIP port. Let´s say I can forward ports 5062-5063 for SIP so that it F!B can be called at "[email protected]_of_the_fritzbox:5062". Can I set the F!B 7170 to listen for SIP at 5060-5064 e.g. and how? Thanks! H.