As per subject, I've installed an Optus SIM in my GPS Tracker and even with device restarted a few times and SIM status showing active on the optus account.
Hi @Saady, thanks for getting in touch with us. If the prepaid SIM is active, there might be an issue with the GPS recognising the sim card. It might be best to double check if the device is compatible on the Optus Network.
Does the tracker work via SMS, mobile data or both? I'm guessing its mobile data, in which case you will have to set the correct APN in your tracker. See here.