The original list of Windows Phones eligible to test out the Technical Preview of Windows 10 for Windows Phones only included 6 phones. Now Microsoft has announced a longer list for the second flight, including Lumia 1020, 1320, 1520, 520, 525, 52, 530, 530 Dual Sim, 535, 620, 625, 630, 630 Dual Sim, 635, 636, 638, 720, 735, 810, 820, 822, 830, 920, 925, 928 and Icon. Also included in the Microsoft Lumia line: 430, 435, 435 Dual Sim, 532, 532 Dual SIM, 640 Dual SIM and 535 Dual Sim.

That list is subject to change. If Microsoft finds a bug during testing they can choose to pull a phone from the program. If you’d like to be part of the test of the technical preview on your phone, click here to learn more about the Windows Insider Program and how to sign up.
Among the features of Windows 10 for your Windows phone are improved speech to text, a better photo app, improved notifications and better customization options.
~ Cynthia
I was just came across you mentioning “Text2Speech” -to where I’m quite an experience user of that particular feature to say a few facts follows: –
Windows itself needs a better TTS on “ALL-Windows-Devices-in existence”
As iPad originally made a clearer TTS and “even better” still when an update came to iPad sometime last year improving upon voice “Tone + Speed” from 450wpm into 601wpm TTS “precise superior voice control to spoken clarity at faster speeds enables understanding to faster listening speeds – as compared to average human effort speech would slur above 270wpm -even world fastest talkers omit a lot of vowels to sacrifice for speed- though it’s so great to see you mention a better text2speech (TTS) for win10 on phone – it figures the attention as most people are now “Phone users!” it’s all in the game of technology -a convenience to make life easier > “speed up devices + speed up our minds”