A simple solution is a free Google phone number/voicemail. Have your office number forward to it. The voicemail can have an employee or your voice recorded on it which adds a personal touch. The message can be easily updated to keep it contemporaneous. You also can have a transcript of the message emailed and/or texted to you or a designated employee. This also avoids the situation where you or an employee take a call with kids crawling all over you, etc.