Where do smartphone IMEI-checking services get information from?

When you insert a SIM and "activate" your device for the FIRST time, and the phone "searches and connects" to your carrier's network, your phone transmits its IMEI number to the carrier and this is stored as "data" onto the carrier's database, specific to the cell*** in which your device is at that moment. *** A cell is a area which is served by a particular cell phone antenna tower. As you move from one place to another, and the signal level from one cell weakens, the phone automatically switches the cell for a better connection. This "cell" gives the mobile, the alternate name "cell phone". Now, this information is relayed to the carrier, not only when you move from one cell to another, but also each time you use the SIM card with a different device. This is stored, complete, with timestamps, effectively giving you the activation date (which is the first timestamp on the database). Law enforcement and security agencies just need to tap out a particular subscriber's database to get information such as the current device the person is using and his current cell location. It can also help them blacklist a stolen device, fi the original owner of the device requests them to do so. What will happen is, the theif won't be able to register to ANY network/carrier on the blacklisted device, as each time he activates it, the blacklisted IMEI is relayed to the database. IMEI: Now the IMEI consists of a TAC - http://en.wikipedia.org/wiki/Type_Allocation_Code - which gives manufacturer-specific information. This effectively is a batch number of sorts. Thus it can give you the manufacturing/commissioning date, location etc. The IMEI also consists of the FAC (optional) and the Serial Number (which is the ID of THAT device). Warranty coverage areas may be deduced from this SN upon contacting the manufacturer to know which location/country THAT device was manufactured to be sold in.