Our app has a 'contact us' section, from which the user can dial our call centre. At the moment it goes through to our switchboard. We'd like to provide them with a few buttons which would route the user to the right department, but we only have one external number. We're thinking about writing a service so that the app could hit an API to register the department that the user has selected before it opens the call URL. Then when the call comes through, a plugin for the call centre software can look up to see whether the user has registered a department, and put them straight through if they have.
The problem is - what can we pass to the API that we can recognise later? We don't have the phone number in the app (or do we?) and we don't have a device ID when we're the callee. I know there's a UIDevice class reference but there's also some info that you can pull from the address book. Is there a full list anywhere of all the information that an app has about the handset?
I think it's easier to just use exensions (phone_number,extension) in order to let your call centre software route the call to the appropiate department. Phone information is really unreliable (some owners/devices/networks might block caller id).