Chosen Solution
If my old phones sim is in a new not activated phone will it keep miss reading it as not being there?
No, your non activated iphone should be able to see your Sim regardless. Try several times, it might be just it needs a few tries, maybe something not perfectly fitting in place. You can also try letting Sim inside and reboot your phone, sometimes that does the trick. Check that your SiM is clean and contacts are shiny, maybe give it a wipe with a clean cloth and a drop of alcohol.
