Motorola V300

Hey guys, I noticed that on my V300, when I set a custom RingerID for an address book entry, the same ringtone is played for both a call from that person and a text message. Is there anyway to get the default ringtone for text messages to play instead? I'm wondering if this is a bug or just the way the phone works. It's hard for me to differentiate what's a voice call and what's a text message 😕 Thanks!