Expanding on the simple approach above, let the caller know who they've reached. This will not only eliminate people leaving voicemails by mistake, but it will reassure the caller that they have called the number they intended.
16. Hi, you’ve reached [X Business Name]. Our regular business hours are [State opening hours]. If you need to reach someone immediately, please call [contact’s name] at [cell phone number]. If not, leave your name and contact information and a representative will get back to you when we re-open.

To activate your new AT&T Voicemail Service by dialing your telephone number from the phone assigned with the feature, follow these steps: Dial your 10-digit telephone number and press * while the greeting message is playing. Create a passcode. Record your name. Record your personal greeting. Record your busy greeting. Enter *VM (*86). Tap the Call button. Follow the setup tutorial, which will walk you through selecting a password and recording both a voice signature and greeting for your voice mailbox. Note: If you hear your own or a system greeting, you’ve already set up your voicemail. From the Home screen, tap the Phone Key in the Quick Keys bar. (The Phone application can also be accessed from the Applications screen.) Dial *86 or press and hold to dial your voice mailbox. Follow the setup tutorial. Enter a password. Record a voice signature and greetings for your voice mailbox. Call your Straight Talk phone from a landline phone. When your voicemail begins, press “*” (star key) on your landline phone immediately. Enter the PIN you use to check your Voice Mail from your Straight Talk phone. Listen to the instructions.
This is a test. This is a test of the Answering Machine Broadcast System. This is only a test.