The only problem we had with our cell phones in Canada was dealing with Bell, it's system would simply not recognizes some USA phone numbers, like my credit union. We have Verizon service.
If your debt card has a MasterCard logo on it you'll be charged a 1% surcharge when using it outside the USA, it will show up as a international trans-action fee, MasterCard didn't do this in 2015 when we traveled through Canada but did this past summer, 2018.
My Costco Card wouldn't work at any Costco in Canada but worked fine at any USA Costco stores, a mystery at hand.
We were never asked about fruits or vegetables coming or going, just money, guns, pepper spray stuff like that.
