If you create a call answering rule but don't specify an action, your caller will hear the following prompt: "You have reached the mailbox of . Please call back later. Goodbye." and the call will end.
“Hello! You’ve reached the voicemail of [your name], [your job title]. I’m currently either away from my desk or on the other line. Please leave your name, telephone number, and a short message after the beep, and I’ll be sure to get back to you as soon as I’m available.” Press and hold the 1 key to access the voicemail system. When you hear the recorded message, press the # key to bring you to the system menu. Press 4, for the Personal Options followed by 2 for Personal Greeting. Follow the prompts to record, listen to, re-record and save your greeting. How do I change my voicemail number on Samsung Galaxy s8? Find “Voicemail number” Press Phone. Press the menu icon. Press Settings. Press Voicemail settings. Press Voicemail number. Save voicemail number. Key in +61414121121 and press OK. +61414121121. Return to the home screen. Press the Home key to return to the home screen. Dial voicemail: Press and then hold on the envelope icon displayed on the main screen. Enter Your Accounts Password: Enter the password if prompted. Delete voicemail: Tap 7 on any voicemail and it will be deleted successfully. Open the dial pad on the device. Open the application drawer and scroll through to find the Phone app. Dial Voicemail. Tapping the number 1 and then hitting the green phone icon at the bottom should call Voicemail. Enter a password (if there is one). Skip through messages. Delete a voicemail. Log into Google Voice. Click on the gear icon. Select “Settings” from the menu options. Click the “Voicemail & Text” button. Click “Record New Greeting” in the Voicemail Greeting section. Enter the name for the greeting you are going to record. Select forwarding phones. Click “Connect.”

Voicemails are recorded on your network as audio files and are downloaded to your phone. They are then played back in the usual way, just through the phone app rather than through the music app. Any voicemails you have are visible in the Voicemail app and should be able to be played back by pressing the play icon. This doesn’t always work, though. Here are some fixes you might try.
All that being said, as voicemail is still thing, and carriers do offer it with every account, iPhones support voicemail. Here’s what you need to know if you want to set it up.