Hello. My mother lives with me, and my sisters call in sometimes. I find it works best if they talk about their pets (my mother always loved the pets we had). They always seem to want to talk about themselves in present time. My mother can't connect with that. It's better to talk about old times that feature the loved one. "I am thinking about making a coconut custard pie today, Mom. Your pies were always so delicious! I remember when you always made one for X when they visited, because if you didn't make one, he'd ask you why!" or "I remember when we used to go swimming by the lake, and you were the lifeguard, but you couldn't swim! No one ever thought about that!" or "I remember when you taught me how to drive. You were so patient with me when I screwed up. I was grateful you were willing to take the time with me, and I'm so grateful now to have had such a skilled driving teacher, given the crazy drivers on the road." "I remember how beautiful you were in that red halter dress that was so stylish. I'm that age now, and I couldn't begin to wear so gracefully that dress you used to wear. You're a knockout, Mom!"
That is, I suggest you tell stories about things you remember that either tend to praise your elder or else make a joke that the elder herself or himself used to make. Calling up those old family stories or often-discussed events will usually prompt a laugh, or even a comment. Yes, you have to become the storyteller. But you should see the expressions of delight on the other end. They are so welcome to the ones giving care on the other end.
Lovely to hear you still want to connect with your elder. Connect on their terms, and you'll bring them such delight. Everyone loves praise.
This sounds very like SPECAL (Contented Dementia by Oliver James, which I have found very helpful conceptually as well as practically, and is recommended by our Memory Assessment Service). I don’t think he says anything about phone conversations as such, but I suspect some of the techniques he recommends could be useful.