Qualcomm's patent fee is the chief culprit that dual-card dual-standby mobile phones do not support dual telecom cards. Qualcomm holds all the patents of CDMA technology. Although CDMA is no longer used in telecom 4G, CDMA network is still used to make phone calls and send text messages. If both card slots of a mobile phone support CDMA network, you have to pay double the baseband fee.
Extended data:
Dual-card dual standby mobile phone, ten northern provinces, it is recommended to combine mobile+Unicom; In the southern region, it is recommended to combine mobile and telecommunications. For domestic operators, "Northern Unicom, Southern Telecom", the traditional sphere of influence of Unicom in ten northern provinces, has better base station coverage, while Unicom's CA has the best performance and the fastest network speed. The south is the traditional sphere of influence of telecommunications, and the signal coverage will be better than that of China Unicom.
In April of 20 18, Bruce Lee, vice president of Huawei, also announced that Huawei's mobile phone finally broke through the new technology and took the lead in supporting dual telecom dual-card VoLTE function, which means that not only dual telecom cards can be realized, but also high-definition calling technology can be supported. Since then, the communication baseband is finally not subject to Qualcomm.
References:
Baidu Encyclopedia-Double Card, Double Standby and Double Pass