Sympathies! My DH travels a lot (the US this week), and although he tries to call, he often doesn't manage it. I spoke to him for two minutes last night, first time since he left on Monday morning, and I will see him tomorrow evening but probably not speak again until then. I text him the rest of the time and he texts back, which he prefers to email since going into the email means the work is there too.
One thing that he does though is really pack out his time - maximum meetings etc, usually eating with colleagues/ clients. Maybe this is the case with your DH too? If my DH didn't do this he would probably have to extend every trip by a day. He used to phone more, but have longer trips, i.e. the US used to be Sunday-Saturday, it is now Monday-Friday, which is much better for him and for us. So he has given up free time while he is away, but is home with us sooner.
It might be worth mentioning that your DC would like to hear his voice though, maybe one or two calls? Then it sounds like you are thinking of them, but obviously you benefit too! Now my DS's are 11 and 9 they both have a cheap mobile so that they can text DH and receive texts back from him too. I also find texting good for sending a quick 'loveyou' which goes down well, and usually gets a response.
Regarding the evenings, when he is in the country we have two regular evenings a week that we will all eat together, so he knows that he has to be back by then. These are set in stone, so he knows he has to contact me if he will be late. The other evenings we plan for us to eat together after the DC are in bed.
He has never been in the habit of phoning during the day from work, but since he never manages to take more than 5 minutes for lunch, he is genuinely busy - a 10 minute phonecall will make him ten minutes later home.
It has taken me a long time to get to this point though, and certainly when DC were younger it got quite lonely at times. I tend to be really busy in the evenings when he is away, doing all the jobs that need doing, so that we can all enjoy the time together when he is back as much as possible.