I dunno... when it's 3am and my tones go off, 98% of the time I forget to even bring my phone with me.... let alone try to use it while responding to the hall. Interesting idea though.
My department was one of the earliest in Canada to adopt IAR. It's a great tool. You program your department's number (the phone number to IAR that is assigned to you) into up to 6 phones that are registered on your user profile. (That's one of the few downsides - multiple responders living in the same dwelling or sharing the same phones can only register a phone to one responder.) The system picks up on the first ring, says "Enter 1 thru 9", and waits a couple seconds. If you enter a number, that response code is accepted, spoken, and the system hangs up. If you don't enter anything, the default response code is assumed, spoken, and the system hangs up. Calls typically last 11 seconds in our experience.
Our codes are set up with 1 for "Responding to Station", 2 for "Responding to Scene", 3 for "Responding to Station - Delayed" (meaning we will not get there within our target time, which is encoded in our profiles), and 4 for "Responding to Scene - Delayed", and 9 for "Cancelled". We're considering adding 8 for "Not Responding", so you know that a member has heard the page but is not going to attend. Default is 1. So I can pick up my cordless phone at home, push the IAR speed dial, and just set the phone down. When the line drops at the end of the call, the phone goes back into standby mode. Or, I can do the same with my cell - dial the speed dial, and put the phone back in my pocket.
The screen at the station (or anyone viewing it on our secured Web portal) shows the estimated time it will take for callers to get to the station (or scene). In the setup of your profile, you tell it the length of time it will take you to get from the location you plan to most often be in, to the station. For me, since I live 12.0 km away from the station, I put in 15 minutes. (I have to pass thru a village with a 40km limit) So, if I were to call in right now at 09:11 MT, it would say on the screen that I would arrive before 09:26.
It's a nice system. They plan to have mapping and applications for smartphones available within the next month or so (something that other services like Active911 have right now).