[chongli]

It’s really a paid service in all markets. You can’t send SMS for free in any country. You need to at least be a subscriber to a cell network or some SMS only service. Whether individual providers decide to offer unlimited flat rate SMS or not is a pricing decision, but none of them offer free messaging to none-subscribers.

[mikhailt]

There are US services like Google's Voice, TextFree and TextPlus that has unlimited text messages, I used to use it before with friends without having cell networks for a few years.