The LG6000 - the phone I used to carry - whas a multimode (tri mode or quad mode, don't recall).

To our freinds over the pond...mobile phone service in the USA is very, very different. Aside from the fact that phones are "locked" to only work on the network of the seller, and SIM cards are NOT interchangeable, you also pay for incoming calls.
As far as emergency calls - any cell phone, activated or not, can and will sucessfully dial "911" (our emergency number) if there's ANY cell service at all. As far as "roaming" goes, if you "force" your phone to roam (which is a big pain in the buttocks) you end up paying MUCH more for your calls, because automatic roaming programming is the only way they allow roaming for "free".
Another big problem in the USA is that the cell network isn't very good. Even the so-called "best" network (Verizon) has major gaps in coverage, and in areas where you supposedly DO have covereage, calls dropping or failing to connect are common.
I was in Grand Central Terminal, New York City, last week. Not a country backwater, this is the largest (in terms of tracks and platforms) passenger railway facility in the world.
I went downstairs to the food court to grab a cup of coffee. And there was no cell service. Here I am in the largest railway station ON EARTH in one of the largest cities in the world, where the corporate headquarters of Verizon is located, and my phone has NO SERVICE.
I know this was a "pro cell phone" article, and I still think they are handy, but in the USA at least, they can be maddening.