אם הפעמון לא עובד, תתקשרי אליי כשתגיעי.

Because the sentence is addressed to one female person.

Both תתקשרי and תגיעי are 2nd person feminine singular forms.

• תתקשרי = you (feminine singular) will call / call
• תגיעי = you (feminine singular) will arrive

If you were talking to a man, you would say:

• תתקשר
• כשתגיע

If you were talking to more than one person, you would usually say:

• תתקשרו
• כשתגיעו

Hebrew usually doesn’t need subject pronouns like you, I, she, etc., because the verb form already shows who the subject is.

So תתקשרי already means you (feminine singular) call / will call, and תגיעי already means you (feminine singular) arrive / will arrive.

You could add את for emphasis:

• אם הפעמון לא עובד, את תתקשרי אליי כשתגיעי.

But normally that sounds unnecessary unless you want contrast or emphasis.

In everyday Hebrew, the future tense is very commonly used for commands and instructions.

So:

• תתקשרי אליי = call me

  This is completely natural.

There is also a true imperative form:

• התקשרי אליי

But in modern spoken Hebrew, the imperative often sounds more formal, more literary, or sometimes sharper. The future form is usually the normal conversational choice.

This is very common in Hebrew:

• תבואי מחר = come tomorrow
• תגידי לי = tell me
• תחכי רגע = wait a second

אם means if.

It introduces the condition:

• אם הפעמון לא עובד = if the bell/doorbell isn’t working

So the sentence has this structure:

• Condition: if the bell doesn’t work
• Main action: call me when you arrive

Because לא עובד describes the bell’s current state or functioning, not a future event.

In Hebrew, just like in English, devices and systems often use work to mean function:

• הטלפון לא עובד = the phone isn’t working
• המזגן לא עובד = the air conditioner isn’t working
• הפעמון לא עובד = the bell/doorbell isn’t working

So עובד here means working / functioning.

Also, פעמון is masculine singular, so the adjective/participle is also masculine singular:

• עובד

If the noun were feminine, you’d use:

• עובדת

Literally, yes: הפעמון means the bell.

But in this context, it most naturally means the doorbell.

Hebrew often uses פעמון in context where English would specifically say doorbell, especially when the situation is obvious.

The ה־ at the beginning is the definite article the:

• פעמון = a bell / bell
• הפעמון = the bell

It is definite because both speaker and listener understand which bell is meant—the bell at the door.

אליי means to me.

It is built from:

• אל = to / toward
• -יי / -י = me

So:

• אליי = to me

With להתקשר (to call / to phone), Hebrew commonly uses אל:

• תתקשרי אליי = call me

You may also see the spelling אלי.
Both represent the same word; אליי is a common spelling in unvocalized modern Hebrew because it makes the pronunciation clearer.

כשתגיעי means when you arrive.

It is made of:

• כש־ = when
• תגיעי = you (feminine singular) will arrive

So literally:

• כש + תגיעי = כשתגיעי

In Hebrew, short words like this often attach directly to the next word in writing.

A more separated and slightly more formal version would be:

• כאשר תגיעי

But כשתגיעי is very natural and common.

Because the arrival is a future event.

In English, we say when you arrive, not usually when you will arrive, even though the event is in the future.

Hebrew is different here: after כש referring to a future event, Hebrew commonly uses the future tense:

• כשתגיעי = when you arrive
• כשתראי אותו = when you see him
• כשתסיימי = when you finish

So this is a normal Hebrew pattern, even though it doesn’t match English grammar exactly.

Usually it means when you arrive, but in context it can also carry the sense of once you arrive.

So in this sentence, it naturally suggests:

• Call me when you get there
• possibly with the nuance once you get there

If you wanted to make immediately upon arrival more explicit, Hebrew might use something stronger, such as:

• ברגע שתגיעי = the moment you arrive
• איך שתגיעי = as soon as you arrive (more colloquial)

But כשתגיעי is perfectly normal here.

Sometimes people do say כשאת מגיעה, especially in casual speech, but כשתגיעי is the clearer standard choice for one specific future arrival.

Compare:

• כשתגיעי = when you arrive for a future event
• כשאת מגיעה = can sound more like when you arrive / when you’re arriving, and may feel more present-like or habitual depending on context

So for this sentence, כשתגיעי is the most natural and standard form.

It has three parts:

1. אם הפעמון לא עובד
   = the if-clause / condition

2. תתקשרי אליי
   = the main instruction

3. כשתגיעי
   = the time clause telling when to call

So the logic is:

• If the bell doesn’t work,
• call me
• when you arrive.

Hebrew word order here is very natural and straightforward.

Because the sentence begins with a conditional clause:

• אם הפעמון לא עובד, ...

In standard writing, Hebrew uses a comma here just as English often does after an opening if-clause.

In very casual texting, people may leave commas out, but in normal written Hebrew, the comma is appropriate.

You would use the masculine singular verb forms:

• אם הפעמון לא עובד, תתקשר אליי כשתגיע.

Changes:

• תתקשרי → תתקשר
• כשתגיעי → כשתגיע

Everything else stays the same.

A helpful approximate pronunciation is:

• אם — im
• הפעמון — ha-pa-a-MON
• לא עובד — lo o-VED
• תתקשרי — tit-kaSHRI
• אליי — e-LAI
• כשתגיעי — k she-ta-GI-i

A few notes:

• הפעמון has stress on the last syllable: -MON
• תתקשרי also has final stress: -SHRI
• תגיעי has a noticeable break between the last vowels: ta-GI-i, not just ta-GI

That last word is often the trickiest one for learners.