for ringtones convert the mp3 clip to an amr and it will give you no trouble at all.
If you have the nokia pc suite then you can use the multimedia player to convert and I know the alcatel pc suite converts also
I have a Motorola and I use Nokia Multimedia Converter 2.0
Nokia Multimedia Converter 2.0, including an enhanced user interface and support for 128 kbps video bit stream, is a tool for converting common multimedia files (such as AVI, WAV, MPEG, and MP3) into standard 3GPP/AMR, H.263, wideband-, and narrow-band-AMR-supported formats for use in mobile phone applications such as MMS. Original and converted multimedia and 3GPP/AMR formats can be played on a PC.