You can indeed use different Voicemail Greetings per Profile status(Academy(Basic): Voicemails Slide 4) and then utilize Profile auto switching as mentioned in the link leejor provided but do bear in mind that if you need to have a third different voicemail greeting for weekends you would probably have to utilize the Custom 2 profile status (Default name: Business Trip) and have the user manually switch to it before the weekend. This will of course mean that it will be applied from the time the user switches to it(eg Friday afternoon). To combat this you could perhaps use a dummy extension somehow but that really depends on your requirements and what exact behavior you're looking for.