I dont thnk so.
As you have it setup, a special ringer for your girl, as in a 1-person calling group. This will also setup the SMS as well. Sounds like your girl sends you cute sms while your in the same room and ya dont want her to notice the special ring, hehe. Just josh'n ya, I do the same thing; although when my ex - whenever we were in an argument - called I'd set the callid group on my Ericsson T39 to send all calls by her to the voicemail (even if she #31#dialed me). Hilarious.
Seriously though, I think the best help would be at a popular cellular forum like howardforums. 1st do a search under motorola for your Razr & in FAQ's - just like you would in this site. Then also check under your provider - if you bought your Razr locked to your provider. I'm sure you'll find a definative answer in no time.
Good luck. And always be ready to answer ur girls call. Once she knows that its a special ring for her number, and you barely answer it, she'll be on your back about it. hehe, cheers.