I have manged to get the E61 to connect to an Asterisk (http://www.asterisk.org) on a public IP via a GPRS connection. But when I try to use WLAN, with the same user details (of course having unregistered the GPRS connection) to connect to the Asterisk box I see that the WLAN connects, but then I get a 'Service Not Available' message when I attempt to register and the WLAN disconnects. This is true if I am trying to connect to an Asterisk on my same LAN segment or outside of the network on the WAN.

Are there any settings I am forgetting here?