A subscriber identity module (SIM) card phone is a device that uses an integrated circuit to provide mobile services to consumers. One of the hallmarks of this type of phone includes the ability for the card to be easily switched and used between devices. Consumers can also change carriers and monitor their cell phone usage with this type of device and a prepaid SIM card, respectively. Unlocking these phones to use across networks is a lucrative industry, and can provide a user the opportunity to inexpensively obtain a high-end cell phone.
One of the benefits of using a SIM card phone is that its chip can be easily swapped between devices. This means that consumers who want to switch or upgrade their phones can do so without having to wait for their carrier contracts to expire and an upgrade opportunity present itself. Instead, they can independently shop for devices that are compatible with their carriers, purchase them, and use them as soon as they install their SIM cards into their new cell phones. This process can simultaneously save consumers money, and provide them with more product selection, as the device choices provided by carriers are often limited to their branded inventory.
These phones are also popular amongst those who enjoy or anticipate the need to switch carriers. Often times, rate plans can vary significantly between competitors, and consumers may find that they want to switch to different company to take advantage of new features or better prices. Should they opt to do this, they can keep their SIM card phone during and even after the transition. Consumers need only verify that their potential future carrier be one that relies on the same technology to provide services.
A prepaid SIM card phone can save consumers money while also giving them the opportunity to manage multiple numbers. These types of devices are similar to their post-paid counterparts in that they provide the same types of services and features, but require advance payment before services are rendered. Many countries refer to this advance payment method as "credit." Choosing a prepaid plan is helpful for those who want to closely monitor their cell phone usage. Their ubiquity and relative inexpensiveness make the purchasing of new SIM cards easy and affordable for those who anticipate needing to change phone numbers often.
A large part of the SIM card phone industry is devoted to the unlocking of devices so that they can be used on networks other than the ones to which they were originally assigned. This is a controversial, though lucrative, practice, and one that allows consumers to use their phones however they please. Many times, it also gives a consumer the opportunity to purchase a high-end SIM card phone for a fraction of the market price.