Remote extension can't place outgoing calls

I have freepbx 2.4 and asterisk 1.4.15 running with about 9 internal extensions (in the same building on the same subnet, etc). I am trying to set up a cisco 7940 as a remote extension. I’ve followed this guide: (static IP on freepbx, sip_nat.conf is proper. ports 5000-5100 and 16000-30000 forwarded to freepbx box).

I have a cisco 7940 setup as a remote extension (or, that’s what I’m trying). It will register, I can use it to call extensions connected to my freepbx, and I can call it from the pstn via it’s did, but I cannot use it to place outgoing calls to the pstn. This pastebin shows the CLI output (verbosity 10) when I try to place a call: The cisco acts like it has placed a call, but it just returns me to dialtone instead of connecting me to the call. I don’t get why I can receive calls but not place them. From what I’ve read, it’s normally the opposite with remote SIP extensions. Any help would be much appreciated.

incidentally, connecting to the extension via xlite produces the exact same behaviour, so I don’t think it’s a cisco 7940 thing