Huawei c8817l Phone is unable to answer phone using 2G network

1, as shown in the picture, in the 4G signal bad situation, the terminal will use 3G or 2G Internet. When the user is connected to the Internet in 4G and 3G, he can answer the phone.

2, when users use 2G online, but not to answer the phone.

3, turn off the data switch, the normal answer to the phone.

4, the mobile phone card to another 2G mobile phone, 1X Data Services online, can answer the phone. After the card changer test, found that the problem in the mobile phone card, replace the new 4G card, all normal.