Most carriers offer voicemail for free. However, some carriers may limit the number of voicemail messages you can have stored. But this shouldn’t be a problem because not many callers leave voicemails anymore.
Before you record your professional voicemail message, take a quick peek through these examples for some inspiration:

Whether you’re out for the day or are off for the week, the first rule of an out of office voicemail greeting is: let callers know when you’ll be back! You’ll save them the frustration of continuing to call and yourself the hassle of listening to redundant voicemails. It’s also a good idea to set the expectation of whether you are answering messages while you’re away, and who they can reach for assistance in your absence.
From the Skype for Business desktop app (if you are running Click-2-Run build C2R 8201.1002 or later), select Set Up Voice Mail. Change your Call Answering Rules You can change what options your callers have when they reach the voicemail service; get disconnected, hear your greeting, record a message, choose to be transferred to the number or user you select. Change your prompt language This is the prompt language that is played to callers. For list of supported languages, see Languages for voicemail greetings and messages from Skype for Business. Configure your Out of Office greeting This is the customized greeting message that is played to callers when your status is Out of Office. This option can be activated "Always," when you have an active "Auto Reply" in Outlook, or whenever you have an out-of-office calendar appointment.  Where you can get your voicemail messages from