Ring Tones for Blackberry 7100g

My wife and I just bought individual Blackberry 7100g cell phones. She would like to add a ring tone. The manual indicates you can. Cingular web page of phones does not have a check beside ring tones for the Blackberry (which might mean you can not). I tired to go to a free ring tone service and download a tone to test installing one. It did not work. However we only have telephone and email subscription. If I subscribe to MEdia.net does that allow downloading ring tones and then will it work on the 7100g? Thanks for any help...