Has anybody been able to get incoming calls working in Asterisk on this router?  I haven't, 

.  I'm wondering if it's the router or more likely my own ignorance.  
I've forwarded ports to the Asterisk server in the router config.  I've told Asterisk to use a small amount of rtp ports, and told the router to forward those to the Asterisk server.  I've tried enabling and disabling the rtsp and sip ALG.  Is there anything else I should try that I'm unaware of?  
A2 with 1.21b2