Ptera Wireless does not provide a Newsgroup Server.

There are NewsGroup Servers available, some for free and some for a fee.

This website is a source that tracks free newsgroup servers...
http://freeusenetnews.com

This website does not charge to use 50MB of their service but you are required to pay a to sign up...
http://www.teranews.com
They also offer packages for higher usage.