Setting for T-Mobile Data preferred over WiFi Data (but WiFi preferred over roaming)?

patentrace

    My usage situation requires the following, and I'm looking for settings that wouldn't have to be changed daily to accomplish it.  I have a recent T-Mobile WiFi Calling capable phone running Android 7, and could use help finding the right settings for the last two below:

     

    WiFi ON - success

    WiFi Calling/SMS ON - success

    WiFi Calling/SMS preferred over Cellular Calling/SMS - success

    International Calling/SMS ON - success

     

    Cellular Data/MMS ON - success

    T-Mobile Data/MMS ON - success

    Data Roaming ON - success

    Domestic Data/MMS Roaming ON - success

    International Data/MMS Roaming ON - success (but it would be nice to find a way to turn this off without also turning off domestic data roaming)

    T-Mobile Data/MMS preferred over WiFi Data/MMS - HELP

     

    My problem is that enabling WiFi calling means enabling WiFi, which in turn often prevents my phone from using enough T-Mobile Data from my US home to balance out my accidental international data roaming from use of Canadian cell towers that are quite close to my US home (and seemingly stronger as if Canada allows higher antenna output than US FCC?).  Finding a setting to make T-Mobile Data/MMS preferred over WiFi Data/MMS would resolve this issue.  Any idea as to how?

     

    Also, does anyone know of a way to self-check my international data roaming usage (as opposed to T-Mobile data or even domestic data roaming usage)?

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