ALBANY (AP) – Sen. Charles Schumer says a survey by his office has identified more than 4,000 cellphone dead zones in upstate New York.

The Democrat said Wednesday that the number shows the need for cellphone service providers to upgrade their network reliability and speed. He says dead zones are not only an annoyance but can harm tourism, local businesses and even public safety.

Last winter Schumer asked upstate residents to report the presence of dead zones to his office so he could create the tally. His survey found the greatest number in the Hudson Valley, followed by the Albany region.

The information from Schumer’s office has been sent to telephone companies. Schumer says wireless carriers have a responsibility to fix the problem.