We are all agreed that the future of mobile is in data not voice (and text as that is the same legacy bucket)
I remember seeing an announcement from BT as it was back then, probably about 1991 saying that the volume of data calls had exceeded voice calls on their network. They were talking about modem calls here, but today voice is carried as a data stream, and is a small contribution to data volumes on networks.
This reality is not reflected in the pricing structures. Voice is charged depending on the destination of the call, so a local call is cheaper than a international call (sometimes) but with data (Internet) there is no concept of distance. You go to a web address which may have a country designation but that may be connected to a server farm anywhere in the world.
When we get into roaming then the cost differentials really show up. So the old world voice services, that have been traded, and commoditised over many years, although still priced at huge markups over the cost of the same call on a local account, are consistent and predictable.
Data roaming charges, however are the wild west, with per megabyte charges 10 to 100 times that of local accounts. There is a chance that smart-phone users will be educated by these charges to avoid roaming data at all costs. This is an option on most smart phones, certainly Android has an option to disable data connectivity when roaming, and I believe iOS has the same option. But the usefulness of these phones then drops to a dumb phone.
Andrew Gill had a nice post on his London Calling blog about avoiding inflated roaming charges, mostly by using a local pre-paid SIM card.
My experience from a recent trip to USA and Canada is that there is enough free WiFi available in the Americas in most places so you don’t need to do this. All the hotels had free WiFi for guests, most coffee shops, thorough in some places you need to open the web browser and click an accept T&C button before it works. And in airports, free access for the first hour.
Sadly this is not the case in the UK where almost every access point wants to milk your credit card before allowing access. But there is the popular FON system, which because it is enabled by default on all BT Home Hubs, is widely available.