What is a mobile phone network card?

In fact, this concept is relatively general. You can say that the mobile phone card that is mainly used for surfing the Internet is the network card. Strictly speaking, the SIM card of wireless Internet access service specially sold by mobile companies can access the Internet with mobile phones or with computers through wireless devices. When using this card, you have already opened the internet service and a certain amount of traffic. But with this card, you can't answer the phone (the phone function is off) and you can send text messages. For example, the monthly flow 10G card issued in Shandong this year (available 1 year) only sells for more than 70 yuan when it is cheap. You can use your mobile phone to surf the Internet. Where there is a 3G network, you can connect to the 3G network, but there is no telephone function, so you can only surf the Internet.