OK, not a generic device, the dial-in number has to point to a Hunt Group.
The hunt group needs a bunch of members.
Those members are the numbers you configure in the SIP Server Configuration as "Extension First" and "Extension Last".
SIP domain is the IP address of the controller.
SIP Port is 5060.
And just to clarify, if your dial-in number is a speed call pointing at the AWV hunt group, or if it's a generic device with a permanent call forward or call re-route pointing at the AWV hunt group, the System Options form is where you put the number that people actually dial.
For example, if you have controllers in different area codes, you will probably have a different number for AWV for each controller, and all those numbers point at the Hunt Group - the Hunt Group number is not exposed to anybody.