shouldistillhope, that is a very dangerous situation to worry that your 7 year old is being left at home alone, with no supervision, regardless of if there is a phone or not. Children of that age need adult supervision. I have twin 6 year old daughters. I would never leave them alone in the house for any reason. So much could happen when they are left alone.
BKS is right, you need to take control of the situation, before something bad happens. Your children and their safety is top priority.
M: 8 yrs T:14 Twins:7 S:5 BD:'NLILWY': Feb/2013 Mar/Apr/May: MC June: "living in limbo" Sept 12: H moves out Oct 20: reconciling Jan-Feb 2014:MC Feb 2014: separating, and H moved out.