Note: If necessary, delete an existing greeting (limit of 2 greetings) to make room for the new greeting: Tap the Menu key, tap Delete greetings, tap the check box next to the desired greeting, and then tap Delete. Tap the Record icon to record your greeting. Tap the Stop recording icon to stop recording.
Make sure your voicemail status is set to On. Set your greetings: Standard Greeting: Select the greeting that you just created. This will be the main greeting that callers will hear when they are transferred to your voicemail. Alternate Greeting: You can also set an alternate greeting to switch to when you are on vacation or in a meeting. By

“Hi! You have reached [your business]. All of our staff are currently busy helping other callers. We understand how valuable your time is, and rather than keeping you on hold, we will make sure to call you back.Be sure to leave us a detailed message with your name and number. We will return your call within two business hours. Thanks!”
If someone is listening to your voicemail greeting it's only because they intend to leave you a message. Don't make them listen to 3 minutes of rambling in order to do so. Plus, you're more likely to deliver a clean, professional read if you stick to shorter greetings. If more specific information is needed, direct callers to where they can find it on your website.