how to stop roaming call while using wifi because airplane mode is off?

Solution
If you are using WiFi, then the only way your calls would be roaming (wow not heard that one in a while) would be if you are making outbound calls or answering inbound calls. Otherwise, you get no charge for any inbound that you don't answer. To make calls using the WiFi you would need an app for that (like hangouts, or others). If you make calls from the phone itself while roaming then it is on you for the charges.

If you want to not get any calls when you are out of the main service area, then the only way is to either turn off the phone, or turn it to airplane mode.

Now, if you don't want to hear any incoming calls that are through the phone plan (but still get any calls from/through the app you are using on WiFi), then you could...
If you are using WiFi, then the only way your calls would be roaming (wow not heard that one in a while) would be if you are making outbound calls or answering inbound calls. Otherwise, you get no charge for any inbound that you don't answer. To make calls using the WiFi you would need an app for that (like hangouts, or others). If you make calls from the phone itself while roaming then it is on you for the charges.

If you want to not get any calls when you are out of the main service area, then the only way is to either turn off the phone, or turn it to airplane mode.

Now, if you don't want to hear any incoming calls that are through the phone plan (but still get any calls from/through the app you are using on WiFi), then you could turn off the sounds for regular calls. This would not effect the sounds for the WiFi app calls.

Again, there are no roaming costs unless you answer a call when out of area, or you make a call.
 
Solution