Firing a timer in a background app and showing UILocalNotifications

I've written an iPhone app to display available bandwidth for my satellite modem, but I'm interested in allowing the timer to continue to fire in the background (though with much greater time between ticks) and display UILocalNotifications during events such as reaching a 20% remaining limit. I think the answer to this is "You can't", but I'm posting here just in case I'm wrong.

PS: Stack Overflow alwa开发者_如何学运维ys shows up first on my Google Searches. You've got a very great community here. Thank you for all your help. :)

This is currently impossible, but a "known issue" being investigated by Apple's engineers.