You can set the voicemail speed dial on your LG phone through the phone's menus. LG makes two types of phones. The company's regular phones run a propriety operating system, while LG smart phones use Google's Android operating system. Android phones always have the voicemail setting in the call settings menu, unless the carrier has opted to hide the setting. If you have two models of LG regular phones, the setting is usually in the same place.
Regular LG Phones
Open the main menu and select "Message."
Select "Settings" and open "All Msg."
Open the "Voicemail #" option and type your voicemail number.
Press the "OK" or "Select" button to save the setting.
Android OS Phones
Open the main menu and touch "Settings."
Tap "Call settings" and open "Voicemail settings."
Type your voicemail number and touch "OK."
Refer to your phone manual if you cannot find the voicemail setting in your phone.