No longer just a simple device for placing calls, the mobile phone is now a must-have item for most people. To promote market penetration, many of these multimedia, high-tech handsets are sold at a discount, or sometimes even given away.

However, the sales incentive system that underpins these low-cost models has been drawing fire for the way it shifts the cost of subsidizing new handsets onto the shoulders of subscribers.

Following are some basic facts about the system: