Can a student who did his undergrad from US and is currently pursuing Masters, file for H1 under the undergrad quota? I've a friend who did his undergrad in math and is currently doing his masters under F1. He wants to file H1 under undergrad catagory. My question is, is it possible to file H1 while you are in F1? 
i'll appreciate your answer.. 

Yes, you can.

I believe so. Don't we all do that? I mean, most of the students here who apply for H-1B after graduation, are still under F-1 status, though with OPT and all.

Once you get the H-1B your status will change from F1 to H-1B.

If he applied for OPT, he should have qualified for 27 months, because he is a MATHS major.

 Thanks all for your reply.. Actually he decided to join masters and become F1 student rather than extending his OPT. But now he wants to file H1. Someone was telling that he has to get a CPT first or so.. I just don know how does this workk..

I brought up OPT as a point to illustrate that most who study here apply H-1B under F1 status. I don't think H-1B has a requirement to have a CPT first.
These are legal matters that should be best checked with experts though, are you willing to put your status in hands of novices like us?