Might have to set the APN and all that so your data connection will work. Not sure though... You should be able to make phone calls right away, however.
If you haven't yet, I'd try asking Telus. They'll probably tell you the standard stuff like they don't support unlocked phones, etc, but should be able to inform you in a general sense what steps you'd have to take. Howard Forums would be a good place to look as well.