I've just bought and received my third dual sim phone which I specifically needed to be Telstra Next G (850Mz)data compatible and in case others are interested wanted to detail what I got.
Both my SIM cards are Telstra and I only need Next G data on one of the two SIMs. My preference would have been for the Samsung Galaxy Note Dual Sim version but I could not confirm that it was 100% Next G compatible. (btw I would be interested in others experience as owners of the Samsung Galaxy Note Dual Sim working on Telstra Next G for data)
I ended up getting a ThL W7plus (sku41663) for $US228.99 from a Russian based Chinese Phone supplier! The build quality is better than the previous phones and it has Android 4.2 which I am happy with. The first SIM provides Next G (3G) data speeds. It is a dual sim (passive) and so if I am on a call on one SIM and someone calls me on the second SIM, then the second call will go to voicemail. It arrived with the language setting switched to Russian and I was able to switch it to English by following the icons in the settings. My only caution was that although the website I bought from had the best selection of Dual Sim phones I have found when it came to ordering there were versions that they could not supply for some reason and I had to change me order two times.
My second dual sim phone was $260 (incl. delivery) for a BLU Studio D510 dual SIM from ebay. It was Telstra NextG compatible and although not the latest version of Android or the best specs in the world (and a no-name Chinese brand without the tick) it worked well. The older version of Android started to bug me.
My first was the Alcatel 918D. I had it for several months and bought cheap via COTD for approx. $100 and then Telstra Next G went and shut down the spectrum it used for 3G.
Do these phones come with Google Play preinstalled?