Lumia 640 lte cortana

[Stephen Wright1]

What works and what doesn't

 

[xandros9]

I don't follow. Compared to what?

Everything that's supposed to work works?

 

[Harrie-S]

I also do not really understand the question but "Hey Cortana" will not work because you need a snapdragon 8xx for this feature.
Furthermore Cortana is not (locally)available for every country. So if you still want to use Cortana you need to change some settings.
There is also a difference in what Cortana can "do" because some countries have an alpha version and some a beta version.

I hope this answers your question.