YK25 came out BEFORE YK24. YK25 was primarily meant to fix issues with certain ERIs showing the roaming indicator even when the phone was not. YK24 added the VCAST music service to phones that came out prior to models with the new firmware already in place. On the horizon is a new firmware update ZD08. I don't know if anyone has it yet, or exactly what it fixes. There are only speculations, but nothing really as far as music capabilities I believe.