Ukuphi?

The kids in my maths class decided to help me learn, and came up with the following phrase:

Uyakuphi?

From isizulu.net:

where
-phi, kuphi

whereto
ngaphi

Accordingly:
where are you? - uphi / ukuphi? (sg)
                       - niphi / nikuphi? (pl)

where are you going?  
uyaphi / uyangaphi?  (sg)
niyaphi / niyangaphi? (pl)

The children and the dictionary disagree on whether 'uyakuphi' means 'where are you'/'where are you going'. Any answer, or does it depend?

These words bring to mind songs:


Mowbray Kaap by Freshly Ground  (isiXhosa and English)
A popular one with a refrain 'Ukuphi!?" which I now can't find - any help?
Searching on google, various other songs entitled/containing 'ukuphi' or 'Ukuphi na?' came up.
Ukuphi by Tshedi