First thing that I would try is pulling battery and SIM for about 30 sec.
What sort of phone is it?
If it is an iphone, make sure that 3G is enabled as Koodo does not have 2G service
(also if an iphone, put it into airplane mode, instead of pulling the battery and SIM card)
If this does not work then try calling tech support - they will probably have you pull the battery and SIM also but they have several things in a checklist to go through to help you get your phone working