they cannot provide a telephone connection out of japan. " our NTT- contract is not international, why don't you use the app Line ?" But they are not aware, that Line needs a broadband (internet) connection, that is expensive in many countries (where we go to holidays). IN Japan, we need a WiFi-router for 100€ per month.
Wife's mother, 91, lives in a care center. She has a phone, android, that my wife set up with a
very simplified interface, just a couple big icons on the home screen to call either my wife or her sister. Just wake it, and tap to call one or the other.
That plan runs about ¥1000/month, I think it includes a certain amount of call time, in addition to data. Those calls would be local/domestic or course, but they're also just voice calls. Setting up LINE on the same phone would be almost as easy, would not use the normal voice call time, and no international charges.
No broadband required, just the typical data offered on that basic/cheap phone plan--you get both voice and data. And with LINE, you can either call with video or just audio, send pics/videos back and forth, and so on.
Since you're not here, I guess the challenge would be getting her the phone, the proper setup, LINE registration/activiation, and also getting her trained on using it.