Why do sims of one operator work differently?

Question

Yota

There are two sims, one from the phone, the other from the USB modem.
There is a piece of hardware Huawei USG 2110, if you insert the sim of their phone and put apn Internet.yota everything works, if you put the sim from the modem and register yota.ru or Internet yota - it doesn’t work. What could be the problem?

Answer 1

Checking the IMEI of the device during authorization on the network.