Depending on what cellular provider you have and where in the world you are, the process may differ a little bit. Searches can likely be made to find the specific instructions for your specific provider. All in all, however, most of the set-ups are fairly similar and shouldn’t take very long at all. So without further ado, let’s take a look at the ways to set up your voicemail on the iPhone 6S.
When on vacation, provide your callers with a return date and a back-up contact person to accommodate emergencies. This prevents you from potentially damaging a valued relationship while you enjoy some time off.

If you use voice mail or an answering machine to answer calls when you can't, make sure that you have a professional message recorded, that does the same thing as tip #3, and gives callers any other pertinent information before it records their messages. Update your voice mail message as needed.
Last, make sure you keep this voicemail account up to date, especially if you have some kind of "out of office" message, telling people where you are. Michael Hyatt updates his voicemail message every day-- it may seem excessive, but it lets his callers know that he regularly checks his voicemail, cares about messages he receives, and is likely to get back to them.