Police in Bradford are using Bluetooth technology to try and catch drug dealers in the city.
Officers are using the system to send messages to residents' mobile phones, asking them for information about drugs in their communities.
The messages will also be sent to people's laptops.
Insp Darren Minton of West Yorkshire Police said it was "imperative" that they heard from anyone who was aware of drug-dealing activity in their area.
"If we know what is happening in your neighbourhood, we can do something about it," he added.
Anyone with information is asked to contact West Yorkshire Police or the Crimestoppers charity.