If you persistently can’t save your greeting, you may need to reset your phone’s network settings. The iPhone needs to access your network’s data connection to save changes to your voice mail configuration, and if it can’t connect to 3G or 4G, it won’t save the changes.
Business voicemail greetings are likely to vary by company. Consider these specifics to create a professional voicemail greeting that works for your needs.

Step 2: If your phone is able to use Visual Voicemail, you will see a Set Up Now button. If you don’t see this pop-up or your phone starts to call the voicemail, your phone will not be able to use Visual Voicemail at the moment. You can call your providers and see if you can get it if you want.
Not all carriers support Visual Voicemail, but most major ones do. Visual Voicemail will work automatically as long as you’ve set up regular voicemail on your iPhone. Tap the Phone app icon to open it.In the bottom toolbar of the Phone app, tap the Voicemail icon.On the voicemail screen, you’ll see a list of all the voicemails people have left you. Tap any voicemail on the list.When you tap a voicemail on the list, it will expand to show a set of controls as well as the iOS transcription of the voicemail. If you want to read the transcription without hearing the voicemail, you can do that right here. Alternately, you can tap the play button to hear the voicemail. Save And Share Voicemails