Both your land line and your cellular phone have a voicemail applications. The voicemail answers any phone call you are not capable of receiving. When first setting up your phone you may have recorded your own greeting, or you may have retained the default recording. If you want to create your own message or change your current message, you can delete the greeting currently stored as your voicemail.
Navigate to your voicemail option if using a cell phone. Usually there is a hot button on the phone that takes you directly to the voicemail listing. If not go to the menu and select "Voicemail." If using a land line press the "Play Voicemail" button.
Listen to the recorded voicemail instructions. To change your greeting you are given a specific number to press. Push this number.
Press the number on your keypad symbolizing "Yes" when asked if you want to delete your current message. You are told the exact number you need to press here (the number can change from make and model phone).
Select to record your own message if you want, or leave it as the mechanic default message. Wait for the instructions to read out your message. Once complete, the message is played back to you. Save the message if you like it or select to re-record it. Once complete you can hang up your phone.