In Germany in the year 2010, nearly half a million “silent SMSs” were sent by the federal police, the customs, and the secret service “Office for Protection of the Constitution.”
German law enforcement agencies have been “pinging” mobile phones. Such pings only reply whether or not the targeted resource is online or not, just like an IP network ping from a computer would.
After making their pings, the agencies have been requesting network logs from mobile network operators. The logs don’t reveal information from the mobile phones themselves, but they can be used to locate the cell towers through which the pings traveled. And thus, can be used to track the mobile targeted.
Requesting such network logs was a legal gray area until 2007, when Germany amended its telecommunications surveillance act.
Just how many other countries consider this type of tracking to be a gray area?
My post showed it is active in the US in September.
Only way to stop the tracking is to remove the battery.
Silent messages, often called silent SMS, stealth SMS, or stealthy ping, will not show up on the display, neither is there an acoustical signal when they are received. However, at the mobile provider some data is created (for example, the subscriber identification IMSI). This kind of message is sent especially by the police to locate a person or to create a complete movement profile of a person.