With iOS 7, several new features have been added to Apple's personal digital assistant, Siri. One of the most convenient is the ability to check your voicemail for you. So now, if you miss a call, rather than tapping your way through the Phone app, you can simply ask Siri.
How to have Siri check your voicemail
Press and hold the Home button on your iPhone to activate Siri.
Say something like Check my voicemail or Do I have any voicemails?
Siri will then tell you if you have any messages in your Visual Voicemail. If so, you can tap on any one of them in order to play them. You may be asked to enter your passcode if you have one.
That's all there is to it. While Siri can't play voicemails for you, she can certainly help you get to them just a little faster!