Phone Call Recorder - ACR is "free." It trumpets that all call recordings, incoming or outgoing, even photo calls—meaning FaceTime calls—are unlimited in length. But that's if you upgrade via in-app purchase to the pro version for $59.99.
Website: https://toolbox.iskysoft.com/iphone-recovery/change-voicemail-on-iphone.html

These business voicemail greetings will do the trick. 10. "Hello, you've reached [X company]. We can't take your call right now, but please leave your name, contact information, and reason for reaching out, and one of our team members will be in …
After setting the number on your voicemail, you must also record a personal voicemail greeting. Follow the steps below. Start the Phone app. if you don’t see the numeric keypad, tap “Keypad” at the bottom of the screen. Tap and hold the “1” for about two seconds until the phone automatically calls voicemail. Immediately tap “3” to access voicemail settings. Listen to the options. On most voicemail systems, tap “2” to start the process to record a new greeting. The current personal greeting will play; then tap “2” again to record a new greeting. Say the greeting you want, and tap “#” when you’re done. To save the greeting, tap “1.” The personal voicemail greeting has been set. Hangup the phone. How to setup voicemail using a Visual Voicemail Applications