Checked back again, still no charges....
And for the record when I dial my own number I get my voicemail, like I could leave a voicemail also, I also changed my VM speed dial to 813-200-0200 and I can listen to my voicemail like that....
Also I called sprint to do it on my GF's phone, again they had no problem changing the number the first time...guess I'm just lucky...
Anyway I was curious so I started asking the Rep questions, because my GF really didn't care whether she had it or not...
I asked him if it was against policy to do this and he said he wasn't aware of reason why it would be, but he was just a Rep...
So I guess it all depends on who you get but still, there is no reason this should be against there policy, they don't even mention it and many reps don't have a problem doing it...
Remember YRMV