I am not sure what I am missing here. If you are doing a call through the airplane wifi connection you could already do that. If you are doing a GSM call I do

I am not sure what I am missing here. If you are doing a call through the airplane wifi connection you could already do that. If you are doing a GSM call I doubt that you will be able to have any reception at cruise altitude? This means people will only be calling or messaging shortly before/after take off (which they were doing anyway) which well, changes nothing other than not getting asked by airplane staff to enable flight mode.