A lot of companies and people don't realy appreciate how much training is really needed to operate even the simplest of mobile phones.
I've not really seen any solutions other than making buttons bigger and reducing menu options, I'm sure these are great for those with deteriorating eyesight, but they aren't really offering anything for a person who has never used a smartphone before.
The real solution has to be usable by someone who has never operated _any_ modern technology - It has to be so simple you could maybe even train a dog to use.
An idea of mine is to have a bank of "walkie talkies" - one for each person you wish to speak to.
And this problem is always growing; my parents haven't retired yet, but even they are struggling to use today's on-demand television. What will happen when digital terrestrial TV is shut down and they have to learn to use whatever new interface is on the successor to the inevitably cancelled Android TV.