IPhone not making calls on wifi

Hello Pamwagg,

Thanks for posting in the Apple Support Communities.

We understand how helpful Wi-Fi calling can be, so let's see if the following information can help out. For starters, let's see if this may be isolated to a specific Wi-Fi network. If the network has a weak connection, Wi-Fi Assist may be taking over to try to use cellular data instead. Check out the following information for details on how Wi-Fi Assist works, and you can locate additional details here: About Wi-Fi Assist - Apple Support

How Wi-Fi Assist works

With Wi-Fi Assist, you can stay connected to the Internet even if you have a poor Wi-Fi connection. For example, if you're using Safari with a poor Wi-Fi connection and a webpage doesn't load, Wi-Fi Assist will activate and automatically switch to cellular so that the webpage continues to load. You can use Wi-Fi Assist with most apps like Safari, Apple Music, Mail, Maps, and more. 

When Wi-Fi Assist is activated, you'll see the cellular data icon in the status bar on your device.

Because you'll stay connected to the Internet over cellular when you have a poor Wi-Fi connection, you might use more cellular data. For most users, this should only be a small percentage higher than previous usage. If you have questions about your data usage, learn more about managing your cellular data or contact Apple Support.

If that doesn't seem to be related with this occurring on all Wi-Fi networks, let's confirm Wi-Fi calling is set up with the steps below. In addition, confirm if "Wi-Fi" is displayed after your carrier name in the status bar as this symbolizes that Wi-Fi calling is available. You can learn more here: Make calls using Wi-Fi on iPhone - Apple Support

1. On your iPhone, go to Settings  > Cellular.

2. If your iPhone has Dual SIM, choose a line (below SIMs).

3. Tap Wi-Fi Calling, then turn on Wi-Fi Calling on This iPhone.

4. Enter or confirm your address for emergency services.

Note: Emergency calls on your iPhone are routed through cellular service when available. In the event that cellular service isn’t available, and you have enabled Wi-Fi Calling, emergency calls may be made over Wi-Fi, and your device’s location information may be used for emergency calls to aid response efforts, regardless of whether you enable Location Services. Some carriers may use the address you registered with the carrier when signing up for Wi-Fi Calling as your location. When connected to Wi-Fi calling, your iPhone may not receive emergency alerts.

Lastly, confirm that your carrier still supports Wi-Fi Calling by adjusting to the correct country or region with the following resource. You can then locate your carrier to make sure Wi-Fi Calling is listed: Wireless carrier support and features for iPhone in the United States and Canada - Apple Support

Let us know what you locate if you need further assistance. Confirm if you've tested other networks with the settings matching above, and include any additional helpful information.

Have a great day!