Thanks everyone for sharing. Yes, we do Facetime/Skype, which is easy and great with the kids. Kids are 1 and 4, and the 4 years old misses his dad.
As I said, I know this conference and I know exactly how much free time there is. In any case I have travelled for work too and I find it difficult to imagine a meeting where I could not fit a 5 mins call to my kids. If needed, I would excuse myself to call home, find a semi-quiet place, and call.
He does not travel often, maybe a couple of times a year. Why do you feel this changes how often he would/should call?