How can I stop my iphone5 voicemail from calling me when I have a message?

If I miss or ignore a call, like when I am at work or sleeping, I then get about five phone calls from voicemail to let me know. The number that calls me is 988 on caller ID. How can I stop voicemail from calling me when I have a voicemail? I have checked all notification settings and voicemail settings I can find to no avail. It's annoying because if I happen to ignore a call at work when i am not free to answer and want to listen to the voicemail later, my phone just keeps calling and calling me! The only thing that stops it is listening to the voicemail. Thanks!