Hi, i have a client who needs an iOS and Android app built.

We are in the process of wireframing the app and gathering various ideas etc...

The app is for a large specialised taxi company who have over 300 taxi drivers working for them... It is not a normal Taxi company, they only work for corporate companies and do not taxi the general public, however, please do not let their business model / idea get in the way of the main question that i am asking below :-)

The taxi base (manager) wants to be able to pick out and notify a certain taxi driver, and then click on his name in the app so that the taxi driver is notified about a certain job even when the taxi driver is in the middle of using another app such as Twitter, Whatsapp, Facebook, SMS and so on... (a lot of the taxi drivers will be idle most of the time so this notification part is key to the app)

THE BIG (and only) QUESTION

The taxi company wants to know all of the different Notification options that the app could have / use, when the manager clicks on a certain taxi drivers name...

They don't want to rely on the default iOS notifications (or SMS) so they want to know what other Notification options the app could use:

A - is it possible for the app to make it's own unique sound (even when the app is not on) (i know various email and messaging apps have their own sounds)
B - is it possible for the app to make it's own unique sound (even when the app is not on AND when they have their app on vibrate only) (i guess not but thought i would ask)
C - is it possible for the Taxi app to come alive / switch to when the taxi driver is in the middle of using another app (so if the taxi driver was on Twitter, it would switch to Taxi app if a notification came in
D - is it possible for the Taxi app to play a song on the taxi's phone

Basically they want the notification to interrupt the taxi driver as much as possible (which is exactly what the taxi drivers are asking for) so can you think of any other ideas for notifying them as they really don't want to have to reply on the default iOS and Android notifications... thanks in advance for your help...