What phrases would you use if you made a phone call?
Is it 121th a flat? No. It's 122th a flat. Could you call Anna, she is near. :-)
Is '121th a flat' an apartment? Does Anna live in '121th a flat'? If so, I would replace 'near' with 'in 121th a flat'. Your grammar and usage is good, but the meaning a little unclear. Very Good.
This is Russian children's joke. I didn't know what write.