My husband's children (16 & 17) live out of state. He has been given one phone number to contact them, and for 5 months no one has answered the phone or returned his calls. Emails to his ex have gone unanswered as well. His children do not have email or telephones. What can anyone recommend?

First you say they "live" out of state, but your question is can you take them out of state?

Whose state? If they used to live in the same state has your husband, before she moved or when she moved is when he needed to file in court to stop the move.

Months latter is not when you try to deal with it.

So what does his visitation agreement say, has he filed in court to force her to allow him to visit. To force her to give contact info?
Where does his child support money go ?

First you say they "live" out of state, but your question is can you take them out of state?

whose state? If they used to live in the same state has your husband, before she moved or when she moved is when he needed to file in court to stop the move.

Months latter is not when you try to deal with it.

So what does his visitation agreement say, has he filed in court to force her to allow him to visit. To force her to give contact info?
Where does his child support money go ?

Sorry, I don't know where that heading came from... His divorce was 7 years ago. The two parents started in the same state, but she moved away. Neither parent resides in the same state as the divorce decree. She has full custody, and up until he got remarried to me a year ago, conversation and visitation wasn't a problem. Now no one returns his calls, and he wants to plan a visit in Summer.
Thanks for your prompt response!