Ahoy, Christina!
I can totally relate here! My husband and I have taken five Disney Cruises without our girls, although it was OUR choice, not theirs. I try to call home to check on them every other day as well.
There are a couple of things you can do to stay connected. Be sure to check with your cell phone provider to see what the charges might be in the countries you are visiting. I know that when we are at sea, we paid about $2.50 per minute to call home. It was slightly less when we were in port; I'm pretty sure we bought an international plan just for the month.
If you can find free Wi-Fi at each port, you could Skype for free. By doing this, you get the bonus of actually seeing each other and can have a quick conversation. I know my teens really don't enjoy talking on the phone but will absolutely Skype with me. You can also purchase a
Connect@Sea package on the ship as well. I have found that my kids really don't want to talk to us as often as we call.
I hope this helps with your cruise planning! Please let me know if you have further questions as your cruise gets closer.
Happy Cruising, Tracy V.