Nite (Nokia Internal Tune Editor) is a leaked internal Nokia software for Windows used to author monophonic ringtones. By default, it saves projects in the .h format. Note lengths are in milliseconds and it supports a wide range of frequencies. The beep is a square wave rather than the custom waveform that is used on most monophonic Nokia phones. You can download it here
To compose with this tool, draw notes onto the matrix editor with the right click button. There are three options for notes: continuous (default), natural and staccato. For continuous, drag the cursor over to the right to define the length of the note. To select notes, use the left click button and drag the cursor over the notes you want to select, then if you want to delete the notes hit Delete.
To change the BPM, click the Tempo button in the top left corner. The editor also has an option to play the tune "politely" which basically simplifies it.
You can save the file in the following formats: .h (ringdata), .ota (OTA), .rtx (RTTTL), .evt (Event) and .wav (WAVE). Unfortunately you cannot save to either .rng or .nrt (Nokia Ringing Tone), which are the monophonic formats on Symbian and Series 40 phones respectively.