Here is clip from an email I got from the factory I deal with. This will answer your question, but it doesn't help with the T-Mobile issue. But, the brightside is T-Mobile will be moving away from the 1700 band sooner than you think. By then hopefully LTE will be available in the lower cost phones/tablets.Thanks for this. But if I can ask u a favor? Since u are in China, can u find out if the factories even bother with signal 1700 or will ever? This would be a massive sale point for them. Not to mention wonder news to all Tmoble users.
For the USA market option 2 is what is needed. This will also work in most of the world as 3G. I've been talking with another factory about LTE. It's promising... MediaTek is working on a LTE chipset and it should be available soon. The Chinese probably won't ever use Qualcomm chipsets for some unknown reason. I'll let you know when I hear more info on this.I have got the network frequencies chices as below for your ideas:
2) 850 1900 2100
3) 900 1900 2100
4)800 900 1800 1900
For reference the above freq list is for a MTK6577 chipset. Most of the mass-produced phones in China are made for the domestic market and since they use 2100 band that's what most of the phones roll out the door with. Also, a "domestic" phone in China will not have the Google Playstore and most won't accept it if you find the proper APK files. I work with factories that do mostly export so they have the "international" version of Android and not the "domestic" version and yes they will support and do come with the Playstore pre-loaded.