Are they all the calls? Could it be possible you have the call forwarding enabled? I believe the call forwarding can be cancelled by dialing *73 from your phone. If that doesn't work, it might be *72.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.
Are you saying you want all calls to go to voicemail or only a select few, and are you referring to calls that are set to "send to voicemail" that you want on a special list? I ask because some phones have the ability to send calls to voicemail, but that option is sometimes easily undone by tapping the notification on the lockscreen, and doing so unchecks that call from being sent to voicemail.