Calling issues

Hey there Riyas1611,

Thanks for reaching out to the Apple Support Communities. Just to clarify, while on a phone call using your Apple Watch, you're not seeing the green button or bar at the top of the Apple Watch display to change the call to your iPhone, is that correct?

Answer phone calls on Apple Watch - Apple Support

While you’re on a call

If you’re on a call that doesn’t use FaceTime audio, you can switch a call to your iPhone, adjust the call volume, enter numbers using the keypad, and switch the call to another audio device.

- Switch a call from your Apple Watch to your iPhone: While talking on your Apple Watch, unlock your iPhone, then tap the green button or bar at the top of the screen.

If so, since noticing the issue, have you tried restarting your Apple Watch? If not, give that a try with the steps in this next link here: Restart your Apple Watch - Apple Support

How to restart your Apple Watch if you have watchOS 9

1. If your Apple Watch is charging, take it off the charger.

2. Press and hold the side button until you see the power button  in the upper-right corner of the display.

3. Tap the power button.

4. Drag the Power Off slider.

5. After your watch turns off, press and hold the side button again until you see the Apple logo.

How to restart your Apple Watch if you have watchOS 8 or earlier

1. If your Apple Watch is charging, take it off the charger.

2. Press and hold the side button until you see the Power Off slider.

3. Drag the Power Off slider.

4. After your watch turns off, press and hold the side button again until you see the Apple logo.

While restarting may seem like a simple step, it can often help with resolving some unexpected issues like this.

Keep us updated on the results.

Take care!