Phone calls vs texts

Humbly seeking your advice to better relate to my older family members. In general, do you prefer phone calls or text messages?

(Background: I have some family members in their 60s and above, who tend to spend a lot of time on Facebook. This leads me to believe that they have their phones in their hands often, so I’ll send them a few texts to keep in touch. No reply. But when I actually call them on the phone, they’ll chitchat forEVER.)