[cgonzalez23]

I just got the Treo755p also, I too was having that problem. Here's what you do. Once you install Ringo on your phone, go into the application Ringo and select the people icon on the bottom right corner of the screen. There are two icons you can click on. Select the one with just one person inside the box, should be the first one or the one on the left of the two. Once you do this it will take you to a new screen, Select "new" at the bottom left. After you select new you will be taken to another screen that says "New Friend" on the top tab. Select "Name" this will take you to your contacts, pick out the person you want to set up the MP3 as ringtone for. Once you select the person you must uncheck "match all numbers" otherwise it wont work. Also if that contact has multiple numbers saved on your phone, you must repeat the process for every single number. At the "New Friend" screen you can set up this person to have their own ringtone and sms tone aswell. When looking for the songs, the drop down arrow will give you the option to pick it from your SD card. Hit "ok" and exit out. The next time this person calls you, it won't read "unknown caller". The same thing was happening to me too. I had to do this for all the people that call frequently. Hope this works.