Hi @Laura527, let me see if I can help out here!
If your subscription includes a voicemail service, callers can leave voice messages for you when you can't answer calls. Your voicemail service number is normally saved on your SIM card. If not, you can get the number from your service provider and enter it manually.
In order to enter your voicemail service number manually, open the phone app > Tap the menu button (three vertical dots) > Settings > Voicemail > Advanced Settings > Voicemail settings > Voicemail number.
I hope that helped!
