GSM technology allowed phone configurations to be stored on a subscriber identity module (SIM) card, providing flexibility for users when traveling.

GSM, or Global System for Mobile Communications, was a major network standard in the early cellular network and had about 90% market share worldwide.

Phones can act as Wi-Fi hotspots, sharing cellular network connectivity with other devices using Wi-Fi.

The term ‘cell phones’ is used because they operate using a cellular network, which divides the geography into sections or cells.

The performance of each wireless technology is determined by a number of constraints, including the spectral efficiency of the technology, the cell sizes used, and the amount of spectrum available.

3G technologies were introduced in 1998, providing enhanced capabilities and increased speeds for data communication.

LTE (Long Term Evolution) was developed to converge GSM and CDMA networks into one standard for data transmission, allowing for higher throughput (up to 150 Mbps).

GSM uses time division multiplexing to allow multiple users to communicate over the same frequencies, while CDMA uses unique codes for each call to filter out irrelevant information and focus on the specific conversation.

OTA stands for Over-the-Air updates, which include PRL (Preferred Roaming List) updates, allowing phones to adapt to changing network conditions.

The original 2G cellular networks were circuit switched networks, which were primarily good for voice communication and had limited support for data connectivity.