How do I activate phone purchased from Fido upon arrival?
Welcome to the community!
If you got a new line with a phone it will come activated you just need to put the SIM card in and use the phone.
If you did a hardware upgrade you just need to put the SIM card from the old phone into the new one and you are good to go, with a hardware upgrade Fido would usually send a new pre-activated SIM card if you don't need to use the new card just put it away for future use. If you do need to use it you just need to update the SIM card information online, see here on how to do that.