I'm sure someone will correct me, but my understanding is that it is not so much which ports are open as what is coming in on the open port(s).
Some are generally accepted to have certain uses, eg. 80 is generally the port a webserver serves pages. The tomcat servlet container has a default of 8080 I believe. FTP is 21(?) or 22 I think. You get the idea.
A site asking for a specific port to me would suggest they want to connect to your computer in some way other than through the browser. Which is something you would want to think carefully about.
I don't know any thing about 'dataflame', do you need to install a program to your computer to use the service? If so, 2083 is probably the port they chose to use for what could be a variety of reasons.
Essentially it comes down to "do you trust dtataflame?"