I am a System Administrator. In fact, I am a SAGE Level III SysAdmin.
I am not an Administrative Assistant. I will not let you write down my job title as Administrative Assistant on a hospital admission form. And no, I will not take a message for my boss. If you wouldn’t ask the Mail Server Admin or the Windows Domain Admin to take messages for their boss or make appointments for their boss, don’t ask me ’cause I do the same damned thing they do. Yes, even though I have tits; they let women do other jobs nowadays.
And lest you think I’m making shit up, I’m not the only one:

[4:52p] bethlynn: to be honest, I often say i’m invovled in IT support to non-tech people. No matter how clearly I say “System Administrator” they hear “Administrative Assistant”

I’ve heard this exact same thing from other women sysadmins.