Make sure that you set up your voicemail. To check, dial your own phone number from your iPhone and leave yourself a message. Call your iPhone from another phone and try to leave yourself a voicemail. Go to the keypad and press and hold on the 1, or press the Call Voicemail button. This dials voicemail. Check if you have any missed messages.
There are very few cases in which our telephone answering service would recommend having an antiquated voicemail answer your incoming calls. A Courteous Communications can recommend these 10 recordings for personal use only. Your business callers may not appreciate these voicemail recordings, but your friends and family will surely get a kick out of them.

Now that you know which script to use, how do you record it? Depending on your budget and the resources available to you, you can record the script yourself, use a text-to-speech program, or hire a professional voice actor to record your greeting.
Another worth considering trick is to remove all the old voicemails that are consuming the storage and creating multiple dilemmas like this. To delete the voicemail here are the steps, Open the Phone app. Tap on Voicemail at the bottom tab. Then tap on Edit at the top-right screen. Select All the Voicemails and at last tap Delete.