They usually use a data card.
The essence of portable wifi is a 3G (4G) router, and the internal card is the network card on the mobile phone. Generally, mobile phone cards are not used, but specialized data cards.
How to use Huawei accompanying WiFi 3:1. Prepare a mini-SIM card (large card). 2. Open the back cover of the device and insert the SIM card in the direction of chip down and notch outward. 3, long press the power button to start. After turning on the device, Huawei accompanying WiFi 3 will automatically search for signals. 4. Mobile phones, computers and other Internet access devices can be connected to the network of Huawei accompanying WiFi 3. The default WLAN network name and password can be viewed by opening the rear cover of the product.