Open Phone → Make sure you are on Keypad → Press and hold the number 1 for a few seconds. It will call your voicemail; You can check your voicemails here.
The more personal and specific the question, the more likely it'll get a response. Think about it this way. If you start to have chest pains on a busy city street, and you cry out, "Somebody call 911!" you might get help … but you might not. However, if you were to point at one specific person and shout, "Would you please call 911 for me?" it's almost a certainty that the stranger you selected would grab their phone and dial.

iPhone users have another option: You can send a voice message from Apple's Messages by tapping the microphone button inside the text box (this works only when you're messaging other iPhones). By default, these voice messages last for only two minutes before they are deleted, but you can change that. Either tap Keep under any sent voice message or go to Settings > Messages and tap Expire under Audio Messages. You can set the expiration date to Never, but this affects only your record of the conversation, not the recipient's.
Written by Donato Diorio @iDonato