I have the podcast app Overcast set to download over cellular, as I'm at home most of the time or on a Wi-Fi hotspot; as much as a few hundred megabytes of podcasts per month (from a 10GB allotment) come in that way. In Canada, that might have accidentally cost me a couple hundred bucks. (AT&T reputedly will let you change your plan within the same billing period and re-rate the cost. Several people on Twitter said they had called and had that adjustment made after a trip.)
Verizon has a far better deal for Canada and Mexico: $10 per monthly period including 100MB with $10 per 100MB overages ($100 per gigabyte); for $5 additional, 100 calling minutes, 100 outgoing texts, and unlimited incoming texts are included. Internationally, in over 140 countries, the same deal is $25 per month and $15 extra for the calling and texting options. It also includes unlimited partner Wi-Fi where they have deals.
T-Mobile and Sprint opted for a different approach. Both carriers offer or include unlimited international data usage with a twist: your data uses 2G networks (including 2.5G EDGE), which top out in the low hundreds of kilobits per second. Unlimited texting is included, and calls to anywhere are $0.20 per minute. T-Mobile's Simple Choice Plan includes this option at no cost; Sprint offers International Value Roaming as an add-on or included with its top-tier plan. Sprint also has paid daily, weekly, and monthly high-speed data plans for its included countries: $15 for up to 100MB in a day through $50 for up to 500MB across 14 days. The plans run out of data rather than incur overage fees.
The big difference between T-Mobile and Sprint? Covered areas. Sprint has just a handful of countries, including Mexico but not Canada. T-Mobile's deal spans 120 countries, which includes most of the developed world and beyond.
Google's Project Fi has T-Mobile's footprint and the same parameters as Sprint and T-Mobile for calls and texts, but includes 3G data at up to 256 Kbps. Project Fi charges $10 per GB for all data, including international. The service remains invitation-only, however.
One of these plans may suit, but an alternate is to unhitch yourself from your American carrier's wagon and find another.
Get a local SIM for your phone
The vast majority of iPhones now in use support GSM roaming in most or all of the world. While two cell standards, GSM and CDMA, are in use in the U.S., Apple began making dual-mode GSM/CDMA phones for Sprint and Verizon, our domestic CDMA carriers, in 2011. Over time, the phones expanded to support more frequencies in use for 3G and 4G LTE worldwide.
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