Volte not working

Try to reset network settings.

Have you ever received volte in your a55 with current operator?

Officially they do not support https://www.robi.com.bd/en/personal/volte

Will other operators work on?

Visit Gsm aena website and search your model and see network and its bands..and fdd or LTE

Please reset network setting of both Sim one by one and than reset all settings of your's device in general management settings also Flight ✈️ mode on n off one time, restart your's device without any Sim in slots also interchange Sim in slots, turn off power saving mode then try to it's again. If you like please accept as a solution it's help to others users also,click on 3dots in my reply section and click on accept solution. Thanks.

Your's most welcome to here.

Dear Samsung Member,

Greetings from Samsung Customer Support!

As per your concern, we would request you kindly perform the following steps to resolve your issue.

Network mode should be set to LTE,3G, or 2G (Auto Connect): Path: Settings > Connections > Mobile Networks > Network mode SIM1/ SIM2 LTE/ 3G/ 2G (auto connect).

Reset the network settings- Path: Settings>General Management>Reset>Reset network settings.
Reset settings- Path: Settings>General Management>Reset>Reset settings.

You can reset your device by following the steps from the below link.
https://www.samsung.com/in/support/mobile-devices/samsung-galaxy-mobile-how-to-perform-a-factory-reset/

In case the issue still occurs. Please visit the service center for a physical inspection of your device. You can locate your nearest service center with this given link: https://www.samsung.com/in/support/service-center/

Warm Regards,
Samsung Customer Support