I am going to take a trip to the Northwest into Seattle...then head over to Vancouver BC. While in Vancouver, I don't want to rack up a huge bill for data usage (I use Verizon as my carrier). For an iPhone4....what is the proper and best way (other than to shut the phone off) to avoid data usage? And when I have it in that mode, will I also be shut off from using wifi? Is the way to access the 'network' settings and disable the 'data roaming' setting to the 'off' position? Any other things to do? Thanks.