Hello GURPREET071,
Welcome to the community!
Firstly, you should note that these forums are community-driven and not intended as a venue for customer services. We do not have access to customers' accounts nor would we know what correspondence may have been provided to you.
That said, I'm guessing the notification you received was in reference to using the '3G' network. I understand your device might be LTE-capable (and even 5G-capable). However, the issue is not necessarily not being able to access the LTE (4G) network. In fact, if the device has compatible LTE bands/frequencies (see here), it should be able to access data on that network. Rather, you likely being told it does not support 4G because the device is likely reliant on the '3G' network for calls and text messaging.
You should note that Fido traditionally have not supported certain services (ie voLTE and/or Wifi-calling etc) on devices or versions of devices they do not sell. Though, that does not necessarily mean people had to purchase from Fido. Fido sells the same Canadian versions of devices as the other Canadian mobile providers as well as local box stores etc. As long as the device was the same version as the one they sold, it was possible for those services to be supported.
On the other hand, non-Canadian versions of devices (ie US or Global Samsung S series etc) would likely not be supported for those services. In addition, other devices from manufacturers which are not generally sold from Fido or Canadian mobile providers (ie Xiaomi, OnePlus, Oppo, etc) are also likely not to be supported for those services (see here, here, here, here. etc).
Without voLTE, calls and/or messages would necessarily fall-back to the '3G' network. Unfortunately, Fido/Rogers intends on decommissioning the UMTS/WCDMA network July 2025. After the '3G' sunset, you would likely not be able to use that device for calls or text messaging.
I understand that once the '3G' network is decommissioned, limiting voLTE to only Canadian versions of devices they sell will be problematic for other device users. However, I do not know if, or when, they might allow voLTE and/or Wifi-calling support for non-Fido (non-Canadian version) devices.
Hope this helps 😀
Cheers
