Not true. The background services offered by the OS allow the apps to still receive calls/IMs etc while not in the foreground. According to Apple press release:

Not true. The background services offered by the OS allow the apps to still receive calls/IMs etc while not in the foreground. According to Apple press release: "These services include background audio, so apps like Pandora can play music in the background, and VoIP, so VoIP apps can receive a VoIP call even when the iPhone is asleep or the user is running other apps." http://www.apple.com/pr/library/2010/04/08iphoneos.html http://www.apple.com/pr/library/2010/04/08iphoneos.html