How to change iphone voicemail greeting?

I got the iphone 4s with version 6.0.1 and i'm trying to change the voicemail greeting but when i click on voice mail it doesn't have a greeting option it just calls it and that is all i can do please help

You can also do it by calling voicemail. Just hold down "1" on your phone until it reaches your voicemail and listen to the voice until she says something like "Press blahblahblah to change your voicemail greeting"

With an Iphone, go to your phone app. Then on the far right should be the voicemail option. Go there. In the upper left there should be a button that says 'greeting'. Just use that button to change it!