You can do so by logging in to your carrier’s website or contacting customer service for assistance. Some network providers also let you do so via their mobile app. Go to Settings → Phone → Change Voicemail Password.Enter the new password.
Timing is everything. The moment you receive the lead alert is the best time to make the follow-up call. If you call them days later, your chances of getting them on the phone are greatly diminished. By calling them right away, you’ll talk to more leads which will inevitably boosts sales. Role-play your voicemail scripts so you sound like you’re making your 20th call, not your 1st. Ask your friends and colleagues for honest feedback on your voicemail scripts. Continually review what’s working and what isn’t -- there’s always room for improvement. If you have the lead’s email address, follow up with an email, and let them know in the voicemail you’re going to do so. If you don’t have an email, let them know you’ll follow up with a text.

Thanks for calling Dial-A-Shrink. I can’t come to the phone right now, so after the tone, please leave your name and number, then talk briefly about your childhood and tell me what comes to mind when you hear the following words: orange… mother… unicorn… penis. I’ll get back to you with my diagnosis as soon as possible.
It's important to mention your follow-up plans in your sales voicemails. Sometimes just the knowledge that you'll call again is enough to entice a prospect to respond. Let them know that if you don't hear back from them, you'll follow up in a few days or next week.