Why can't I receive QQ information with 3G signal?

CDMA system adopts unique soft handover technology, which greatly reduces the drop rate of CDMA mobile phone during handover. At the same time, due to the high spectrum efficiency of CDMA, network congestion is greatly reduced and the connection rate is naturally improved. With the development of CDMA network construction in the new time and space, mobile phones will enter a smoother era. The future of CDMA is looking forward to a brand-new space-time CDMA network based on information exchange between people at any time and any place. In the future, CDMA networks can support multi-channel synchronous calls and data transmission services. It can realize flexible and diverse data services such as mobile videophone, videophone conference, mobile e-commerce, intelligent map, high-speed Internet access, mobile online games, digital cameras, video-on-demand VOD, and on-site monitoring. Through a CDMA mobile phone, you can enter a brand-new communication space, let you walk at the forefront of mobile communication in the world, and fully realize the brand-new feeling of "nothing is impossible, only unexpected". A new generation of mobile communication technology, new communication concept, new service mode, new business, new fashion, new enjoyment ... A new time and space of mobile communication with leading technology, rich content, environmental protection and full personalization has come to you. We will go hand in hand with you with sincere service and jointly enter the brilliant new era of future mobile communication. Leading the future world wind-real global smoothness In today's society, people's pursuit of quality of life is constantly improving. With the rapid development of communication industry, mobile communication consumption is no longer limited to a single operator, a single network and pure voice services, and the diversification of communication consumption choices has gradually become a trend. GSM and CDMA are two mainstream mobile communication systems, which are adopted by almost all mobile operators in the world. As the only operator in China that owns both GSM and CDMA mobile communication networks, China Unicom, starting from meeting the needs of consumers, leads the market reform with technological innovation, and takes the lead in advocating and successfully launching the "World Wind" of dual-mode mobile communication products worldwide. Through the guarantee of two networks and free handover, people can quickly enter a new era of mobile communication in which GSM and CDMA networks are integrated from a single mobile communication era. It can be said that "world wind" is not only a technological innovation, but also a change in communication consumption mode. I. "World Wind" Service "World Wind" Service is a brand-new mobile communication service exclusively launched by China Unicom to meet the diverse communication needs of users. It enables you to switch freely between G network and C network with only one dual-mode mobile phone and enjoy the services of both networks. China Unicom's "World Wind" service is realized by using dual-mode cards or dual-mode mobile phones. Ii. Services Supported by Shifeng The services supported by Shifeng are related to the network selected by users: (1) When users choose the GSM network of China Unicom, they can use the services provided by the GSM network of China Unicom to roam internationally in countries and regions that have signed the GSM international roaming agreement with China Unicom. (2) When users choose China Unicom CDMA network, they can use various services provided by China Unicom CDMA network, including using data value-added services based on CDMA 1X (such as Interactive World, Color E, Pocket Broadband, Magic Book, Positioning Star, etc.). ), and they can go to countries and regions where China Unicom has a CDMA international roaming agreement. (3) When users choose the GSM network of other operators, they can use the services provided by other operators' GSM networks and roam internationally in countries and regions that have signed GSM international roaming agreements with other operators. But at present, users can't use various value-added services based on GPS through dual-mode mobile phones. The functional characteristics of "World Wind"-Multiple enjoyment of one machine and two networks! One phone: dual-mode mobile phone dual network: users can choose to switch freely between Unicom CDMA, Unicom GSM and other operators GSM. Multiple enjoyment of value-added services is more exciting: GSM users of Unicom or other operators can increase the use of high-speed and wonderful value-added services provided by CDMA 1X network while retaining the original basic services. Global roaming is smoother: South Korea, North America and other countries mainly use GSM technology. GSM and CDMA mobile communication camps can't roam each other automatically, which really brings a lot of inconvenience to people traveling abroad. The biggest feature of "World Wind" is that it supports free switching between GSM and CDMA networks. Therefore, "Worldwind" users roaming abroad can enjoy the communication services provided by foreign operators' networks that have signed GSM or CDMA roaming agreements with domestic operators. The countries and regions that can roam will be a collection of roaming areas of GSM and CDMA mobile phones in China, which will be far larger than the original countries where single-mode mobile phones can roam, and truly realize the global tour with one phone in hand. Network coverage is more perfect: it is difficult for any mobile communication network to achieve 100% coverage, but the possibility of blind spots and blind spots can be greatly reduced through the guarantee of two networks and free handover. Number reservation is more convenient: dual-mode card users only need one number to use Unicom GSM and CDMA services. Other operators