I worked for a utility and this was an important problem for us as a customer would close their account and move out of a rental and another tenant may move in

I worked for a utility and this was an important problem for us as a customer would close their account and move out of a rental and another tenant may move in and start using gas without having an account with one of the utilities (we don't lock meters on moves, this would be too expensive.) The utility company only finds out something is using gas when a meter is read every few months (we had a threshold.) Here is when we contact the tenant and try to figure out whats going on, unfortunately we don't have phone numbers and sending someone around to check was too costly at the time.