In the Motorola/Compal C155 phone supported by OsmocomBB, we have found a ringtone melody chip called SPMA100B from sunplus.
As strange as it might seem, this is the only part used in the phone for which we have not been able to find any kind of programming information. So if you know anything about how to program this part from software (register map, programming manual, ...) please let me know!
And no, we don't need electrical/mechanical data sheets, thanks :)