gsm 850/900/1800/1900

The two types of cellular telephony radiation use different carrier frequencies and give different frequency spectra, but they usually also differ in intensity, as GSM 900 MHz antennas operate at about double the power output than the corresponding DCS 1800 MHz ones .

GSM phones require sim cards with unique user’s phone numbers from any network provider . Changing phones is considerably convenient when you can simply transfer a sim card into another GSM phone, and it remains useable— making GSM phones directly associated with the unlocked phone concept.

A Global System for Mobile Communication Subscriber Identity Module, or GSM SIM card, is a SIM card that uses the GSM network . Having this card in an unlocked cell phone while using the correct frequency allows a cell phone user to use his cell phone in various countries all over the world.

SIM cards are always used on GSM phones ; for CDMA phones, they are needed only for LTE-capable handsets. SIM cards can also be used in satellite phones, smart watches, computers, or cameras.