Let's say you are in Japan, and you are visiting a friend. So you go to their door and give it a knock. After you hear some movement inside, you will probably hear this phrase too.
Dochirasama desu ka? or Who is it?
Politely tell them it is you by stating your name followed by desu, the polite form of the verb "to be".
So if you are Robert, say
Robert desu. - It is Robert.
If you are Brett, say
Brett desu. - It is Brett.
If you are Julie, say
Julie desu. It is Julie.
After stating politely who you are, and if they like you, they will tell you
Dozo, o-hairi kudasai - which is to say - please come in.
