a TELUS or Koodo brand iPhone 5 should work without unlocking but there are certain restrictions and provisioning that you will have to do to the iphone to get it to work with Public Mobile for data usage.
See here regarding the steps for enabling data.
It'll work, however it has to be activated before on Telus Network, if it was not U should unlock it first, pop up PM SIM to find out
@google6711 Public Mobile SIM card will not work on a Telus Network. In the same way Telus SIM card will not work on Public Mobile network.
Once SIM card is used it can not be reused.
I have iPhone 4S from Telus and it worked no problem! no need to spend extra money unlocking the phone. And i'm pretty sure Koodo will work too