Through the role of various communication services, the world's spatial dialogue is becoming smaller and smaller. These communication services bring people from all over the world closer. The Philippines, the United States, Singapore, Malaysia, Indonesia and other countries/regions use GSM mobile phone or Global System for Mobile Communications standards. In mobile phones, this is the most popular standard.

In this standard, the operator's network leases a frequency band from the 800MHz, 900MHz, and 1800MHz frequency bands, and then allocates it to users. Each carrier frequency is subdivided into eight time slots to make room for more users. There are many electronics companies that produce cheap gsm phones so that everyone can afford mobile phones. Nokia, Sony Ericsson, Samsung Mobile, Apple, etc. are some large companies that produce and distribute locked or unlocked gsm phones to all qualified users around the world.

At the same time, CDMA or Code Division Multiple Access uses channels as the access method. It uses spread spectrum technology and requires a special encoding scheme to decrypt the digital messages contained in it. Countries such as South Korea and Japan use CDMA in their radio communication technology. Compared with GSM, CDMA has great advantages, because the frequency band is more expensive than creating codes, so the implementation cost of CDMA technology is lower. The phone issued by the manufacturing company has a unique code. Many third-party entities that use software to invade phones can convert CDMA phones or vodaphones to GSM. After the conversion, CDMA mobile phones can now be operated by various network operators. This becomes an unlocked cell phone ready to enter the GSM world.