After a long search, I found out how to edit the #1 voice mail speed dial number.
In the phone app, tap the menu icon (three vertical dots in the top-right corner of the screen). The third menu item should be "Call settings". In Call Settings, tap the Voice Mail option, then tap "Setup". Tap "Voice mail number", then tap the key that looks like a left parenthesis character (under the black backspace key) and select P or comma to enter a 2-second pause. Then tap the 123 key and enter your voice mail PIN, followed by the # sign. Select "TURN ON" to save the number, and you're all set. Next time you long-press the #1 key in the phone app, it should dial your voice mail, pause, then dial your PIN.
In the phone app, tap the menu icon (three vertical dots in the top-right corner of the screen). The third menu item should be "Call settings". In Call Settings, tap the Voice Mail option, then tap "Setup". Tap "Voice mail number", then tap the key that looks like a left parenthesis character (under the black backspace key) and select P or comma to enter a 2-second pause. Then tap the 123 key and enter your voice mail PIN, followed by the # sign. Select "TURN ON" to save the number, and you're all set. Next time you long-press the #1 key in the phone app, it should dial your voice mail, pause, then dial your PIN.
Facebook
Twitter
Instagram