Forwarding UDP blocks of ports with a 1720

Unanswered Question


I am attempting to replace an old netgear router with a "real" router, a 1721. everything works great except passing SIP inbound from remote extensions. A normal ip nat inside source static forwarding works for one port, but the voice path RTP addresses are a block of 10000 ports. I have tried without much luck the method shown in my config attached.

I plead ignorance here, as I can't see why this doesn't forward any udp packets.

Can someone enlighten me please?


I have this problem too.
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Giuseppe Larosa Wed, 03/04/2009 - 06:57

Hello Doug,

application level gateway should support SIP translation


The NAT Support for SIP feature allows SIP embedded messages passing through a router configured with NAT to be translated and encoded back to the packet. An ALG is used with NAT to translate the SIP or SDP messages.

see also for more specific config

Hope to help



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