Stop trying to rationalize it; this is not OK, period. If you can't reach your customer via his contact information, too bad, consider him a lost cause. And if

Stop trying to rationalize it; this is not OK, period. If you can't reach your customer via his contact information, too bad, consider him a lost cause. And if it was something critical resulting in the customer's loss of Internet access, you can bet he will contact you then, if he cares.