Prior has been a puzzle, the phone does not support dual telecom cards, because there are two commonly used telecom cards, at the same time if you want to use, then it can only bring two phones a lot of trouble.
Because before Telecom CDMA technology patent fees are more expensive, mobile phone manufacturers should be charged according to the number of Qualcomm baseband, baseband CDMA dual if necessary in addition to double the royalties, but little demand for telecommunications dual card, there is no production of dual Telecom's mobile phone. But as the popularity of 4G, voice calls can go 4G network, on the phone with two telecom card becomes possible.
Telecom first launched 4G VoLTE business card (now in most areas are opened by default), then the last two years with a phone released (open support dual 4G, enable VoLTE call), two phone cards are set to open on VoLTE call You can simultaneously use two telecom card. After opening VoLTE business, some of the original phone call when there is no network problem can also be solved.
If you stick to the original idea, the phone can not use two telecom card, rather than to seek a solution, it will always fall to the original trouble.
With the development of technology, not before some things have slowly become possible, and as a technical person, to continue to focus on development of new technologies.