it could be brooke that he phones. it would make sense- she wants a baby and a family and hasn't lucas always said that that's what he wants as well. he proposed to peyton becuase he wanted what nathan and hayley have and seemingly he's always been jealous of them.
but at the same time peyton has now shown that she wants to marry him as has lyndsy (or however you spell her name) and i must admit that the writers have always wanted peyton and lucas to end up together. from that first meeting you could see it all happening so i think we have to resign to the fact that somehow lucas and peyton will be together