Thorugh IMEI? The closest thing I know of is through cell phone triangulation and which tower coverage vs signal strength. A good example of this is on Verizon phones, where the "Locator" service can be used to find you when you dial 911 or if you so choose, with any call. This is done through determining what towers are nearby, and which direction from the tower you are calling from, along with your signal strength to the tower. But for the most part, any tracking can really only be gotten through 911 lines or your service provider if such information is requested.