Grandparents are proud of their grandchildren. I encourage them to talk about them and ask for updates. To strengthen their special bonds, I help them keep in touch in a variety of ways. We write and mail greeting cards for holidays and occasions. I might set up and dial phone calls, or send/receive e-mails or texts (preferably with images).
Teenage grandkids can teach the their grandparents hot to do text messaging or social media. They often can explain it uni simple terms and show them exactly how to do it. This is a wonderful to way to stay in regular contact with grandparents. It can even be brief contact done on a frequent basis and it will maintain that close connection between the generations.
Even better, video calls, such as Skype or FaceTime. (I recommend using a bigger screen than a smartphone.) And I might even share with them social media posts of their grandchildren. The use of technology may not be in their comfort zone, but as soon as they see/hear a grandchild, all their attention is focused on them.
Here is a very nice video hone on Amazon that is less than $80. What a wonderful gift for a birthday or Christmas. It would be a very thoughtful way to keep in touch. https://www.amazon.com/Android-Tablet-Quad-Core-800x1280-Screen/dp/B01H8LMW7M/ref=sr_1_5?ie=UTF8&qid=1536000141&sr=8-5&keywords=video+phone+for+elderly+for+skype