Some Android Phones support WiFi calling but there's no option in the UI to turn on this feature. For such phones, you can use one of following techniques
$ am start -a android.intent.action.MAIN -n com.android.settings/.Settings\$WifiCallingSettingsActivity
$ am start -a android.intent.action.MAIN -n com.google.android.ims/.ui.WifiCallingSettingsActivity
Download the Activity Launcher app (https://play.google.com/store/apps/details?id=de.szalkowski.activitylauncher) from Playstore. Search for "wificalling" (Without space).
@extremecoders-re, this should be possible to automate further, by utilising the method that I have demonstrated at
stackoverflow.com/revisions/79812863/2. However, first, I would remove the useless dollar:#!/system/bin/sh am start -a android.intent.action.MAIN -n com.google.android.ims/.ui.WifiCallingSettingsActivity