Verizon Communications is offering wireless customers affected by Wednesday’s outage a $20 account credit, apologizing for an hourslong service interruption that a spokesman said was tied to an issue with a software update.

Verizon is offering a very small mea culpa after Wednesday's massive outage, which drew more than 1.5 million reports on Downdetector and lasted hours.

The outage prompted several major cities to advise residents to use other carriers to call emergency services.