Yes, you can. In order to use both 4Freedom Mobile service and your current provider’s service at the same time on the same device, your device must support either 2 SIM cards or 1 SIM card and 1 eSIM.
Keep the SIM card from your current mobile provider installed in your device. Then install either a 4Freedom Mobile SIM card (if your device supports 2 SIM cards) or install a 4Freedom Mobile eSIM (if your device supports eSIM technology).
After you configure your 4Freedom Mobile SIM card / eSIM, you should configure your current provider’s SIM as the primary for Voice & SMS services, and your 4Freedom Mobile SIM as the primary for data.