Cholzhauer,
So, I am just guessing here that you are currently having those phones outpulse that number through Emergency Calling Party Number within their phones settings; if not you would need this set up.
Next you would need to either set the Emergency Extension under Associated Extensions of each phone to use the SIP Trunk Group or set them to 92000 [Default FAC for ARS] and then make sure that the SIP Trunk Group is in Route Group 1's Facility Group. Just to let you know when 911 is dialed from an extension using ARS it will only use what is in Route Group 1's Facilty Group to get out. If the phone doesn't have outgoing access it will still get out, but only after trying a couple of times.
Once you have that set up you can test it by dialing 911 and then telling them that it is not an emergency and that you are testing to ensure that you are getting to the correct PSAP [Public Service Answer Point]. Have them verify the name, phone number, and address of the 911 call and that they are the correct PSAP for that location.
Thanks,
TE