No, I don't think you should ask to speak to your W when calling the kids. I think give it a couple of more months and see if she says more than 'hope you're ok' (or words to that affect). Once you see a little more interest in your safety, and curiosity in what you do, then perhaps you can start by telling the kids to say 'hi' and a hug to mommy from you, and see if that gets anything going. If it does, then ask to speak to her for a couple of minutes - keeping it short at first, and talking about her life mostly.
Or, you could get things going by the odd, impersonal email. It's less intimate than a phone call, and she may feel 'safer' in communicating that way with you? Just a thought.
Just my opinion, but I think you should play this out slowly, trying to let her step closer first.
Keep ya head down out there!
Me:57 H:52 M:28 Got another lawyer last year and filed. D35,S/D twins28,D22 EA4/04 End? Who knows? "Life is like a mirror. Smile at it and it smiles back at you." — Peace Pilgrim