Man is this strange: when I set my DHCP server to assign the Sipura box a fixed IP address, the VoIP box didn't work. When I let it assign an address out of the pool, it did work.
So what happens if you now configure the DHCP server so that the (working) IP is removed from the pool, and have the DHCP server explicitly assign it to the device instead? Does it still work? What if you turn the DHCP client off in the ATA, and try to manually assign the ATA both the fixed IP that didn't work, and the IP that does?
Seems to work for the moment.
There has to be a difference somewhere, whether it is in the DHCP payload, the way a router or NAT engine upstream is treating that IP, or *something*.
Most likely the DHCP payload, the NAT engine in the router isn't likely to treat one IP differently from another. Regards, John Levine, johnl@iecc.com, Primary Perpetrator of "The Internet for Dummies", Please consider the environment before reading this e-mail. http://jl.ly