We are writing apps for Android and so far only use the simulator.
What kind of unlocked phone can I buy that will work in the USA and with a change in the SIM card, work in Australia? What do we look for?
We will have teams in the US and Australia and want to buy the same phones in bulk.
Well, any phone will really as long as you buy it sim free. You should look at some of the newer phones running newer versions of Android. HTC Desires or Nexus one's would be ideal.
I bought new Nexus One at ebay from US customer, and it works fine here in Russia :)
afaik Nexus One works great in other countries, for example also in germany. I assume it will also work in Australia, as long as the net frequencies are supported (I think they are....no warranty)
Any sim free phone should work in both countries. However, I don't suggest you buy the same phone in bulk. It might be better in the long run to get a range of phones so you can test your apps across multiple platforms.
For example, I have a G1 and a HTC Desire. The G1 is running Android 1.6, has a HVGA screen. The HTC Desire has Android 2.1 with a WVGA screen (which is a different screen density).
This allows you to easily test your apps to ensure they work on more than one phone. In addition I keep the G1 because it is relatively slow compared to the Desire, which allows me to test my apps on both fast and slow devices which is something the emulator can't emulate well.