Much better & simpler method: simply phone your own voicemail service. Then one of the options will be to ‘record a voicemail’; after which you can enter the phone number, record & send voicemail.
The importance of voicemail in the customer care sector has not diminished despite the arrival of newer web technologies. VoIP applications let the businesses use voicemail service with flexibility, as it is. The users need not rely on extension terminals when they use VoIP services. A strong internet connection is a prerequisite and the pre-configured phones can be used – both for calling /receiving calls and for automated custom greetings. IVR feature redirect callers to the right virtual extension where their needs can be addressed. This can be done anywhere through a web portal access and an internet connection.

Here’s a simple clinician voicemail script if you want to keep your message to the point. Hello. You’ve reached Highland Family Counseling Services. We are currently unable to take your call, so please state your name, phone number, and a detailed message after the beep. We will return all calls within two business days.
Hi. This is David. I’ve shut the ringers off on my phones and taken a sedative. As soon as I finish this recording I’m going to bed indefinitely. When I wake up I’ll play my messages. Please leave one.