Removing Ringcentral calls from Iphone

Matt, check your extension's Call Handling and Forwarding settings if your cellphone number is listed there.

1. Sign in to your RingCentral online account.
2. Navigate to Settings > Call Forwarding and Voicemail.
3. Under Work Hours, you will see where your calls are forwarded. Your third-party number may be there, which is forwarding the calls to it. Slide the active button to turn it off and click Save.

To learn more about Call Handling, you may visit the KB article, https://support.ringcentral.com/article/9758.html