asterisk users - Sep 2005 - 405 "Method Not Allowed" error

Hi everybody,
I'm curious to know what this message generally
indicates. I have XLite softphones on two different
machines accessing the Asterisk server behind a NAT.
The server is able to find them just fine, but instead
of registering when Asterisk reloads they return this
message back to Asterisk. I feel like I've looked
everywhere but there doesn't seem to be an
explanation...
Thanks,
Tim

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