An IMSI (international mobile subscriber identity) catcher (Stingray), also known as a mobile device identifier, is a controversial tool because it is indiscriminate in whose mobile device is affected. The technology essentially mimics a cellphone tower, tricking all phones within a particular range to go through it. It can be used to pinpoint the location of a specific phone with far more accuracy than data that can be obtained from a mobile provider like Bell or Rogers.
The device also has the ability to capture other data such as numbers dialed from a phone or text messages, and some can eavesdrop on calls and jam phones to prevent them from being used. Police services that have admitted to using the technology, including the RCMP, have claimed their equipment does not capture private communications.