I configured a few voice routers that are directly exposed on Internet. They have access-lists that denies all the sip and h.323 traffic. When I'm scanning the router for example with nmap (syn scan) I get message that the port is open (administratively filtered). I just want to deny any responses on that ports like the and hide my router at all. Is there a way to do that?
The IOS version is 12.4-3h and the router is Cisco 2811.
Thank you in advance.