Most of the handsets (mobile phones) sold in India are one of the following types:
1. Type 1 (most of the handsets in the market sold after JIO launch)
These handsets support 4G connection only on one sim card slot (generally SIM 1), the SIM 2 supports only 3G connection (so SIM 2 will not support 4G connection).
So if you want to use 2 different 4G data connections then you will have to physically change the SIM cards (form one slot to other) every time to you want to change the 4G connection. Please note that in these handsets if you are also using JIO SIM card then it will not work in SIM 2 slot.
2. Type 2 (most of the handsets in the market)
The second type of handsets support 4G connection on both SIM 1 and SIM 2, but at any time only one SIM will work with 4G connection i.e. you can enable 4G on either SIM 1 or SIM 2, the other SIM will then automatically support only 3G connection.
So if you want to use 2 different 4G data connections then you will have go to SIM settings in your phone and first disable the 4G Data on the current SIM and then enable 4G data on the other SIM. You will have to do this every time to you want to change the 4G connection from one SIM to other.
Please note that in these handsets if you are also using JIO SIM card then it will not work if you enable the other SIM card for 4G data.
3. Type 3 (very less handsets in market)
The third type of handsets support 4G connection on both SIM 1 and SIM 2 and both can support 4G connection at the same time, i.e. you can have data connection on both SIM cards at the same time.
In this type of handset you can use 4G data from any SIM. You just have to go to SIM settings and enable preferred SIM for data and standby SIM for data. If the 4G connection is not available on preferred SIM it will automatically change to standby SIM.
In these handsets the JIO SIM card will continue to work irrespective of which SIM you are using for data.
If you are using type 1 or type 2 handset you will face SIM switching problem irrespective of the telecom company.
If you are using type 3 handset then you should definitely get 4G data on your handset irrespective of the SIM slot, you just have to enable it in SIM settings.
Depending on which type of handset you have you can accordingly use your Airtel 4G SIM card. more