There are two main types of networks in the world:
Global Mobile Communications System (GSM): AT&T, Vodafone Code Division (CDMA): Verizon, Sprint, Nextel, Altel
Because the infrastructure is considered, it is built differently – one supports SIM slots (GSM) and the other (CDMA) does not.
Global Mobile Communication System (GSM)
GSM phones can unlock and switch operators, while CDMA operators use network whitelists to check customers. This means you can only replace CDMA phones with your operator’s permission.
In some cases, CDMA phones may have a SIM card slot but only support foreign GSM networks. This means you can not use a Verizon phone with a GSM network in the United States, but you can use a GSM network in another country if you are traveling abroad.
True, there is a merger between GSM and CDMA (T-Mobile and MetroPCS, Sprint and Softbank), but generally, CDMA devices are not compatible with GSM networks.
Multiple Access Code Devices (CDMA)
CDMA networks are common in some regions of North America and Asia (e.g., CDMA networks: Verizon, Sprint, US Cellular, Straight Talk, Unphone). Unlike GSM phones that can be used with an internal SIM card, CDMA phones cannot be used on a SIM card. Switching phones over the GSM network is easy because you need to remove the SIM card and insert it into another phone (new phones will get your number).
This does not apply to CDMA if you can only change the phone with the operator’s permission, but usually, CDMA does not allow you to change the phone.
Based on this, you should know that GSM phones can only be locked to switch carriers, while CDMA operators use network whitelists to check customers. This means you can only replace CDMA phones with your operator’s permission.
The type of tissue before the merger is very important. Network Infrastructure Although CDMA has existed since its inception, the company will merge due to its initial infrastructure.
To find out which operators/networks use this CDMA network, see here: CDMA Network | Unlock the unit
Basic GSM and CDMA standards. Appeared in the 2G era.
GSM covered GPRS and EDGE for 2G years. This network usually uses a SIM card.
CDMA has the CDMA2000 in the 2G era and often does not use a SIM card. You usually have to buy a phone from your ISP and not use it on another network.
3G is out, and every “family” has its own standards. CDMA has EVDO then EVDO-Rev1. GSM includes WCDMA, UMTS, and HSPA.
Lastly, we now use 4G, which is usually the LTE standard. LTE is the GSM standard, but in line with global standards, traditional CDMA networks have also decided to use LTE. So in the 3G era, Verizon and Sprint phones did not have SIM cards, but now they do not. Phones on this network are connected to the old CDMA technology as well as the new GSM technology.
Hope this helps!
CDMA VS GSM
GSM and CDMA are popular technologies that provide multiple access to a single channel. An important difference between GSM and CDMA is the unique GSM for SIM cards used with mobile phones. However, CDMA is used for mobile networks.
Before downloading, you need to know three access technologies: FDMA, TDMA, and CDMA.
The main difference between GSMA and CDMA
- The important difference between GSM and CDMA is that GSM connects to the SIM card, meaning that the mobile phone is in a network with the SIM card inserted in the phone. When it comes to CDMA, the network recognizes the phone with the information stored in the internal memory, and hence the special phone.
- TDM and FDM are technologies used in GSM to track multiple customers in a single channel. While on CDMA, many calls on the channel are indicated with a code (CDM).
- Networking provides all mobile phones in the GSM mobile network. However, in CDMA, each cell in a network has a unique physical channel and code.
- In GSM voice and data can be transmitted simultaneously but not in CDMA.
- Because GSM is used and accepted all over the world, it can be connected, making CDMA cheaper.
- GSM uses GPRS, which provides lower bandwidth if data rates are slower. Conversely CDMA uses EVDO (Evolution-Data Optimized), which provides a larger bandwidth of data frequencies, thus increasing transfer rates.