How to know if the sim is 4G

In line with the developed countries of the world, Bangladesh has also entered the fourth generation (4G) internet technology.
Bangladesh Telecommunication Control Commission (BTRC) officially handed over 4G license to Teletalk, Grameenphone, Banglalink and Robi mobile operators at Dhaka Club in the capital on Monday.
As a result, Bangladesh has entered the age of 4G from today.
With the introduction of 4G technology, customers will get high speed internet service.In that case, your SIM used on mobile should also be 4G SIM and if you want to know if your SIM is 4G you can follow the following steps.
1. Grameenphone:
If Grameenphone operator SIM users call *121*3232#, you will get the return SMS whether its SIM is 4G or not.
2. Ravi:
Robi customers can know only by doing *123*44#.
3. Banglalink ;;
Banglalink customers will get information about 4G SIM in the return message if they send SMS to 5000 by writing 4G from mobile phone.
If the customer's SIM is not 4G, then it is an opportunity to change it from the customer service center of the concerned mobile phone operator.