what's the diffrence bettwen radauth and radaliasauth?

I have made freeradius 1.0.4 wroks well with mysql, I want freeradius to be the gnugk's authenticatior.I am failed to set RadAuth type , but RadAliasAuth can work. I want to know :what's the diffrence bettwen radauth and radaliasauth? In mysql database, what I stored is string( I mean , not digital id ),am I should (and have to) use RadAliasAuth type? the ip phone software what I used is SJPHONE 1.5 free! it will get the message: Registration rejected : gatekeeper security denial! in gnugk's , I got this: RADAUTH RadAuth RRQ auth failed: tokens not found! freeradius is silence, no package was sent to it! whatever, give me your advise, thanks a lot! 　　　　　　　　　　　　　　 zhangyue 　　　　　　　　　　　　　　　　　　　　　　　　　　　　2005-06-23