Learn Hardcore Italian: Per cortesia, citofona quando sei davanti al portone. - Please ring the intercom when you are in front of the gate.

In Italian, time clauses with words like quando, appena, se, finché, etc. usually take the present tense even when referring to the future. So quando sei davanti al portone naturally means “when you are (i.e., when you get) in front of the door.” You can say quando sarai davanti al portone, and it isn’t wrong, but it sounds more formal or emphatic. The everyday, neutral choice is the present: quando sei.

What exactly does citofona mean? How is it different from suona (il) citofono or suona il campanello?

Citofona is the imperative of citofonare (“to ring/buzz via the intercom”), the system at the entrance of many apartment buildings that lets you talk to someone inside.
Suona (il) citofono means the same thing and is very common.
Suona il campanello means “ring the doorbell” and is used when there’s a plain bell (e.g., at a house or at the apartment door itself).
In short: for a building’s intercom, use citofonare or suonare il citofono; for a simple bell, suonare il campanello. All are readily understood.

Is citofona an imperative? How do I change it for formal or plural?

Yes. Citofona is the informal singular imperative (addressing one person with tu).

Informal singular (tu): citofona; negative: non citofonare.
Formal singular (Lei): citofoni; negative: non citofoni.
Plural (voi): citofonate; negative: non citofonate. You can also soften with a conditional: Potresti citofonare…? (informal), Potrebbe citofonare…? (formal), Potreste citofonare…? (plural).

Can I say Per favore instead of Per cortesia? Any nuance?

Yes. Per favore and Per piacere are very common; Per cortesia and Cortesemente sound a touch more formal/polite. All are acceptable; choose based on how formal you want to be:

Everyday: Per favore, Per piacere.
Slightly more formal: Per cortesia, Cortesemente.

Why is it davanti al and not davanti il?

Because the expression is davanti a (“in front of”), and when a meets the definite article, it contracts:

a + il = al → davanti al portone
a + lo = allo → davanti allo stabile
a + la = alla → davanti alla porta
a + i = ai, a + gli = agli, a + le = alle

Is there any difference between davanti a and di fronte a?

They often overlap, but:

Davanti a: physically in front of something (the usual choice here): davanti al portone.
Di fronte a: literally “opposite/facing,” also used for something across from you: di fronte a casa mia c’è una farmacia. In this sentence, davanti al portone is the most natural phrasing.

What does portone refer to? How is it different from porta or cancello?

Portone: the large main door of a building at street level (often heavy, wooden/metal).
Porta: any “door,” including an apartment door: la porta di casa.
Cancello: a “gate,” typically metal bars/fencing. Here, portone means the building’s main entrance door.

How do I specify which intercom/apartment to buzz?

Use a pronoun or add details:

Citofonami (buzz me).
Citofona al mio interno / suona al 12 (buzz my extension / number 12).
Citofona a Rossi, scala B, interno 5 (buzz Rossi, staircase B, apartment 5). Note that with the imperative and pronouns, Italian attaches the pronoun to the end: citofonami. In the negative, it can go before or after: non mi citofonare / non citofonarmi.

How can I make the request softer or more polite?

Per cortesia, potresti citofonare quando sei davanti al portone? (informal, gentle)
Per cortesia, potrebbe citofonare quando è davanti al portone? (formal)
Mi faresti/farebbe un colpo al citofono quando sei/è davanti al portone? (colloquial “give me a buzz”) Adding per cortesia/per favore and using the conditional makes it softer.

Could I use stare instead of essere in quando sei davanti…?

You’ll normally use essere: quando sei davanti al portone. Stare can describe remaining/standing there (e.g., stai davanti al portone finché…), but for simple location in this kind of time clause, essere is the neutral, idiomatic choice.

Is the comma after Per cortesia necessary? Could it go elsewhere?

The comma is optional but recommended because Per cortesia is a set-off politeness marker. You can place it:

At the start: Per cortesia, citofona…
At the end: Citofona…, per cortesia.
Without a comma is also seen in brief messages: Per cortesia citofona…

Are there common mistakes to avoid with this sentence?

Dropping the preposition: not davanti il portone, but davanti al portone.
Using the future by default: quando sei is more natural than quando sarai in everyday speech.
Mixing up vocabulary: citofono (intercom) vs campanello (doorbell).
Imperative/pronoun placement: citofonami (not “mi citofona” in the affirmative imperative); negative allows both non mi citofonare / non citofonarmi.
Using porta when you mean the building’s main door: here portone is the idiomatic choice.