I realize that not everyone is comfortable in not speaking to their child when they call home, but for us, it has always worked well. As a child, as long as I knew where my parents were going and when they were coming back, I was fine. It was when they called home and talked to us that I 'remembered' how much I missed them and would be miserable the rest of the time until they came home. If I didn't speak to them, then I enjoyed my time with my grandparents as we always considered this time with them to be 'our' vacation from mom and dad!
When my (now x) hubby and I traveled, we would call home and check on the kids, but not talk to them. Only one time did I talk to the kids and my daughter, who upon hearing my voice remembered that I wasn't there, begged us to come home and cried the rest of the day and became difficult to handle for a couple of days. When I have been gone and not spoken to her, she has done wonderfully well.
Something that my parents did with us that I also do with my children (yours may be too young for this but you might find a way to age it down) is to show us on a globe where they are going, tell us where they are staying, their flight numbers, when they are leaving and when they are coming home and what they thought they might go to see. They would also check out a book from the library (pre-internet days lol) and we would pour over the book before and while they were gone, wondering what they were seeing in person and what they were bringing back for us as they always brought back something for each of us (they bought according to us individually, not group gifts or the same gift for everyone). My brother still has his wooden marionette puppet and I still have my soft wool blanket from way back when we were in elementary school!
If you feel you can't do without talking to your child, another suggestion is to find out where they have webcams set up in the area you are going to. I know of friends who find where these are and set up a specific time and day to go stand in front of the camera and wave to ppl back home. Some of them hold up messages while others call home and talk to ppl while in view of the camera. (I love to view the cams lol I call it a poor mans vacation!)
Whatever you do, be sure to relax and enjoy yourself and know that you've left your child in good hands.