A Verizon phone outage map shows locations where Verizon Wireless mobile phone service is down or otherwise unavailable. The map is based off of user reports and is color-coded to indicate areas that have a large concentration of reports.
The map uses the color yellow to indicate small potential outages. Areas suffering from larger reported outages shade to orange and then to red, indicating a serious issue. The map is not specific enough to demonstrate which areas of a given city may be suffering the outage, so (for instance) if it is only Manhattan that has an outage, the map still shows all of New York as yellow or red, even if the other boroughs still have service.
At the top of the map, it indicates where recent reports have originated from, which makes it easier to immediately know if a given city has been reported as having an outage. This can help one to decide whether or not an issue is with his own phone or the network as a whole.
The system is based off of user reports, which means it may not always be as up to date (or correct) as possible, but it is still a good way to know if there is a serious outage affecting one's area.