Welcome to the community!
In addition to what FidoCharles mentioned, I believe the voicemail system is different for iPhones. You would need to contact customer service to switch to the iPhone voicemail system. Alternatively, you might consider sending @FidoSolutions a PM. Once they verify some information, they'll also be able access your account.
Hope this helps 😀
You would first need to confirm if both phones use the same type of SIM card. If yes, you can simply put your Fido SIM in your iPhone, restart it and you should be good to go. 🙂
If not, then you would need to get a new Fido SIM to fit your iPhone and update your SIM card directly online on your account.
Hope this helps!