After pressing the Voicemail tab, all of the voicemails stored on your device will display. From here, you’re going to want to tapGreeting located in the top left. There will be two options located on the Greeting page: One option to utilize the default voicemail message and another to record a custom message.
Website: https://iplum.com/blog/faq/how-to-create-custom-or-professional-voicemail-greetings-for-iplum/

There is no way to know who has listened to your voicemail unless the caller leaves you a message.
Home > Phone Systems > Corporate Voicemail Greetings - Bloopers and Best Practices Corporate Voicemail Greetings - Bloopers and Best Practices Want to make the most of your business phone system? Make sure that your greeting to callers is effective. The way any phone system greets callers is critical to the image and presentation of your business. From the initial phone greeting to all callers, through whatever phone menu your system uses - or if you have a live receptionist - through to the voicemail greeting on personal phones, every step sends a message about your company and about you. It is pretty easy to get it wrong - and not an awful lot harder to get it right. "You have reached the Sales Department. Leave a message." This might not seem so bad but think about it in terms of missed opportunities. The chances are that they know they reached the sales department. And they expect to reach a sales person. If your sales team is really so busy thay can't get to calls then at least make it personal. Have messages go to a department assistan who is named. That way a person is involved and the caller has some expectation of personal contact. Tell them good times to call and what information YOU need from them - at very least a reminder to leave their own number! Not too surprisingly, there aren't a lot of real examples floating around on the internet of bad phone systems - but here are a few real and not so real.... Any good voicemail message needs to do a few things: Say who you are very briefly to confirm that the caller reached the right number. Say that you aren't available as briefly as possible. Remind the caller to leave a contact number and identifying information. Ask them to state the issue they are calling about as simply and clearly as possible. Saying who you are is obvious - whether it is the company or a personal message on your extension. While it isn't totally obvious that you should say you aren't available, it is polite and you can include additional information without going too far. If you are going to be gone at another office for a month then you can say that and leave a forwarding number if needed using whatever vacation message function your system may have. But if you are literally just out for a moment then a standard, "I am not available," is all that is needed. Obviously you need to tailor the greeting for the situation. If you are recording a greeting for a common line that is shared then don't leave personal information as the identifier. And don't if you have legitimate concerns about identity. But in reality, most of the time it is better to include who you are. Other optional information that is nice to include is information about when they can expect a call back, email contact info as an alternative and even an answer to an overwhelmingly common query. But those are optional. It is more important to be clear and brief so that the most important information gets across. Once you have a message you like, double check by calling the number to see what the experience is like. It is easy to forget that many voicemail systems include automated instructions that can take up a lot of time BEFORE the caller even gets your greeting. if the automated information is too long, work with your phone system tech to get it changed to somethign useful and appropriate. Adjust your message if needed so you don't repeat anything they already heard. "Hi. This is Joe Smith at Acme Co. I can't take your call right now, so please leave me a detailed message after the tone. Please include your number and your name. Thank you." Brief, to the point and doesn't waste anyone's time. "Hello, this is the Acme Company. We can't take your call in person at the moment. Please leave us a detailed message including your name, phone number and the reason you are calling. We will call you back as soon as possible." "Hi, this is Joe Smith at the Acme Co. I am working in the New York office during July and August. You can reach me there on 212-555-1111 or leave a message here stating your name, number and the reason you called. I will return the call as soon as possible." Hopefully these warning examples and tips on how to do it right will help you improve the way you present yourself and your company to the world.