My calls are going straight to voicemail, and they are not listed in the calls received

If they re not listed in the cal log as missed calls, that means they are never making it to your phone. If they were blocked by your phone either because they were in the blocked callers list or filtered by a focus setting, they would appear in the log as missed calls.

Contact your cellular carrier as recommended above.

Then it's almost certainly a carrier issue, possibly a weak signal or overloaded cell tower in your area. You'll need to talk to your carrier about this.

Regards.