Disable voicemail. This should frankly be the default anyway - voicemail is a relic of the past. Nowadays we have SMS or email for those who want to leave a mes

Disable voicemail. This should frankly be the default anyway - voicemail is a relic of the past. Nowadays we have SMS or email for those who want to leave a message. Alternatively create your own voicemail (using Twilio or Asterisk or similar) and change the call divert settings to divert to your custom voicemail instead of the default one.