Have Phoner installed on machine with public IP address with SIP account hanged on my SIP provider switchboard. Time by time, calls from accounts '100@' or 'sipvicious@' ringing but nobody talking on the other side if I answer such call. Probably some robots scanning for port 5060 listening to misuse some SIP device. 

Is it possible somehow disable direct IP calls to limit to switchboard calls only? Temporarily I changed SIP port to some high number which help me for now, but I expect thay discovered it in future and problem will comeback

thanks, L.

I did not ask for allow/block special peers (listed IP addresses) but for disable/enable direct calls from IP address to IP address (without switchboard usage) similar on this HW telephone:  http://www.odorik.cz/w/_media/well_t20_ghost_calls.png (see red arrow at the bottom)

I am not an expert on SIP, but expect if two people with IP addresses calling utilize switchboard, than SIP messages going through switchboard (incomming to the client PC always from switchboard IP address) but stream could be invoked directly between two public addressed devices. So I expect the add option to block SIP messages incomming from IP deffers from switchboard IP should not be a big deal. But correct me if I am wrong.

L.