Hello lollycav,
To help us get a better understanding of the issue, we’d like to ask a few questions.
1. Does this happen with all callers, or only certain contacts?
2. Does the issue occur when your voicemail greeting plays?
The above details will helps us plan how to proceed.
If the issue seems to be related to your voicemail greeting, you can record a new greeting to determine if that resolves the issue. This link will guide you through that process and may help: Check your voicemail on iPhone
Change your voicemail settings
• Change your greeting: Tap Voicemail, then tap Greeting.
• Change your voicemail password: Go to Settings > Phone > Change Voicemail Password, then enter the new password.
If you forgot your voicemail password, contact your wireless carrier.
• Change the alert for new voicemail: Go to Settings > Sounds & Haptics or Settings > Sounds.
Thanks!