I'd make it about D at first. "Hey.. just called to wish D a happy B-day.... please have her call me back"
That should get the ball rolling. I would imagine that your D wants to talk to you as well right?
Something I did early on was to establish an evening "call time" I call my D's around 6 every night that they are with W.
She doesn't necessarily stick to the same schedule, but I try to keep consistency for the girls. Even when she is at her BF's house, I still talk to them on her cell.
