Samsung

I tried searching for my answer before posting, but couldnt find what I needed. My sister got a T619 & I transferred some of my ringtones to her phone via Bluetooth. They were not able to be applied as her ringtones. I even tried uploading them to a website & downloaded them, but same problem. Is there a way to make my files work as her ringtones? Does this phone support a specific file format other than MP3? Or is TMobile getting snotty like Verizon & forcing you to buy their content?