Greetings Rcuderman,
It sounds like call forwarding isn’t working correctly. We know how important having a working call-forwarding feature is for you, and we will help get you to the right place to find a resolution.
The first thing to try is these steps, which can often resolve this type of issue:
1. Go to Settings
> Phone.
2. Tap any of the following:
• Call Forwarding:
appears in the status bar when call forwarding is on. You must be in range of the cellular network when you set iPhone to forward calls, or calls won’t be forwarded.
On models with Dual SIM, choose a line.
• Call Waiting: If you’re on a call and call waiting is turned off, incoming calls go directly to voicemail.
On models with Dual SIM, call waiting works only for incoming calls on the same line, unless the other line has Wi-Fi calling enabled and a data connection is available. See Set up cellular service on iPhone.
This info is located in the iPhone User Guide: Set up call forwarding and call waiting on iPhone - Apple Support
Call forwarding is a feature offered by your wireless provider. If you still have issues, please contact them for continued assistance. You can use this link for help locating your providers' contact info: Wireless carrier support and features for iPhone in the United States and Canada - Apple Support
Take care!