Yes, though if there's no preexisting greeting the GUI won't detect it if placed in the filesystem. I suspect a database entry is needed for the GUI to "see" the greeting. As a workaround a greeting could be recorded (so that the database entry is present) and the file replaced, but that's getting to be quite a task end-to-end. Also I don't know if the database stores the length of the recordings, which could be problematic during playback if the original and replacement audio files are different lengths. I will do some testing. Thanks. Aug 16, 2018 #4
Your voicemail greeting on your business telephone system is the very first thing your business associates and clients will hear when calling your company. For the first time callers, probably your potential customers, you only got a chance to provide a great first impression that will be provided by your voicemail greeting message. For the ones who frequently call your company, you would want to make your voicemail greeting prompts as efficient as possible in order for you not to waste your client’s precious time in listening to your whole voicemail greetings every time they make a call.

Our last hope to fix can’t record voicemail on iPhone Verizon, AT&T, Sprint and T-Mobile is to reset network settings. Doing it won’t delete or alter the data, only the VPNs, APNs, Wi-Fi Passwords, Paired Bluetooth Devices, and other network-related settings will reset to default. Navigate to the Settings app. Go to General. Tap Reset and then select Reset Network Settings. Enter the password to proceed and confirm Reset.
Hello, you have reached the dental office of Dr. X. We are busy assisting a patient now, but will call you back as soon as possible. Please leave your name, reason for calling, and your number. If this is an urgent enquiry, please call 911. In this case, the dentist is giving a reason for not being available and they’re providing a way to prioritize the patients who need the most help. They’re also leaving an emergency number for the most severe of situations.