In some areas where mobile phone users are concentrated, it is especially suitable to use dual-mode mobile phones, because dual-mode mobile phones can flexibly switch between GSM network and CDMA network, keep the conversation going all the time, and receive signals at the same time, and then combine the received signals to filter noise signals and highlight voice signals, thus obtaining high-quality voice enjoyment. In addition, the dual-mode mobile phone adopts broadband technology, which supports many functions such as call forwarding, call waiting, tripartite conference, calling number display, short message, voice mail, automatic roaming and so on. Because GSM/CDMA dual-mode mobile phone can work in two networks with different technologies at the same time, dual-mode mobile phone undoubtedly has the characteristics of these two network technologies. From a technical point of view, GSM network can bring good call quality and communication coverage in a complex environment with many high-rise buildings because of its high frequency band and strong signal penetration ability. But the system capacity of CDMA network is particularly large. With the same frequency resources, the system capacity of CDMA network can be 8- 10 times that of analog network and 3-4 times that of GSM network. Reference: Due to the sharp increase in the number of mobile phone users, the mobile phone communication network system is in an overloaded state, which will eventually lead to dropped calls, crosstalk, poor voice quality, difficulty in accessing the Internet and other failures. In order to solve the above problems, more and more mobile phone operators and manufacturers are beginning to realize this, and continue to take relevant measures to further expand the mobile phone network system and improve the voice quality of mobile phone communication. Therefore, many mobile phone manufacturers have launched mobile phones that support both GSM and CDMA networks on the basis of mature GSM networks. Although this dual-mode mobile phone has just come out, its appearance has made the dream of mobile phones based on GSM and CDMA come true. Using GSM/CDMA dual-mode mobile phone, users can switch between GSM and CDMA freely, which can effectively avoid the problems of dropped calls, difficult calls and poor sound quality, and is more convenient than using only GSM network. As the name implies, the so-called dual-mode is to work in two network modes, namely GSM network and CDMA network. The so-called GSM/CDMA dual-mode mobile phone means that the mobile phone can support both GSM and CDMA network communication technologies. It can be selected according to the needs of the environment or actual operation. Which network technology can play a more effective role, let the phone switch to which mode to work. If in one mode, the communication quality of mobile phone is not high or there are other bad communication phenomena, you can switch to another network mode freely, which actually expands the call frequency of mobile phone and greatly improves the stability of communication. In some areas where mobile phone users are concentrated, it is especially suitable to use dual-mode mobile phones, because dual-mode mobile phones can flexibly switch between GSM network and CDMA network, keep the conversation going all the time, and receive signals at the same time, and then combine the received signals to filter noise signals and highlight voice signals, thus obtaining high-quality voice enjoyment. In addition, the dual-mode mobile phone adopts broadband technology, which supports many functions such as call forwarding, call waiting, tripartite conference, calling number display, short message, voice mail, automatic roaming and so on. Because GSM/CDMA dual-mode mobile phone can work in two networks with different technologies at the same time, dual-mode mobile phone undoubtedly has the characteristics of these two network technologies. From a technical point of view, GSM network can bring good call quality and communication coverage in a complex environment with many high-rise buildings because of its high frequency band and strong signal penetration ability. But the system capacity of CDMA network is particularly large. With the same frequency resources, the system capacity of CDMA network can be 8- 10 times that of analog network and 3-4 times that of GSM network. GSM network needs to build more than 300 base stations to cover the whole Beijing, while CDMA only needs to build about 80 base stations to achieve this goal, saving limited frequency resources. CDMA has a unique broadband transmission method and strong anti-interference ability, which is suitable for high-speed data transmission services on mobile phones. In addition, GSM network has strong confidentiality and anti-interference, clear sound quality, stable call, large capacity, high frequency resource utilization, open interface and powerful functions. CDMA network also has multipath signal automatic tracking and soft handover technology, which greatly reduces the possibility of dropped calls, which will be very beneficial to users' calls and data transmission during the mobile process. The emergence of dual-mode mobile phones will undoubtedly be the deepest and most practical for users, because the use of dual-mode mobile phones will greatly reduce the phenomenon of roaming calls in GSM/CDMA networks, make incoming and outgoing calls more free, and gain all the advantages of the two network technologies at the same time, so dual-mode mobile phones can ensure mobile phone users to communicate freely in five continents 160 countries. The biggest opinion of mobile phone users on the network is that they often get disconnected. Not only do people suffer a lot in the process of calling now, but some people worry that if the network supports fax in the future, wireless fax will become hidden because of the problem of dropped calls. This is because the mobile phone is hard to pass. When a mobile phone enters the coverage area of another base station from one base station, it first disconnects from the original base station, and then searches for the new base station to contact. This is what is commonly called "disconnect first and then connect". Of course, the time difference of this disconnection is only a few hundred milliseconds, and people can't feel it under normal circumstances, but once the mobile phone enters the shielded area or the channel is busy, it will be disconnected. Now dual-mode mobile phones adopt soft handover technology. During the handover process, the dual-mode mobile phone keeps losing contact with the original base station and contacts the new base station. When the mobile phone confirms to contact the new base station, the contact with the original base station is disconnected, that is, it is connected first and then disconnected, and the possibility of dropping the call is almost zero. At present, in the mobile market of China, several mobile phone manufacturers are preparing to develop dual-mode mobile phones that can be applied to both GSM and CDMA networks in view of the upcoming CDMA network in China. It is planned to see the prototype of dual-mode mobile phone by the end of this year. It is expected that the upcoming dual-mode mobile phone will have many advantages such as fast Internet access, high communication quality, stable Internet access, flexible switching mode and reasonable pricing. When you use this mobile phone to answer a call, it will automatically be in the voice channel state, and once the call is over, it will return to the data channel state. If you are a user who often needs to travel around the world, then a dual-mode mobile phone will make you more unimpeded! Of course, despite the powerful functions of dual-mode mobile phones, we should still believe that GSM mobile phones will still maintain considerable vitality. The first is the advantage of network coverage. GSM mobile phone will have obvious advantages in international roaming and domestic roaming for a long time. Secondly, the advantage of maintenance level and the existence of a large number of experienced and systematically trained manufacturers and field technicians effectively reduce the network operation cost and system risk; The third is brand advantage. GSM mobile phones are widely known, but ordinary users don't understand the advantages of dual-mode mobile phones, which will increase the initial advertising cost of dual-mode mobile phones and increase the marketing difficulty.