من الان نمیتوانم با تو صحبت کنم، چون دارم به مادرم زنگ میزنم.

Yes, the verb already shows the subject.

In نمی‌توانم, the ending -م means I, so من is not strictly necessary.
You could say:

الان نمی‌توانم با تو صحبت کنم...

and it would still mean I can’t talk to you right now...

Including من can add clarity, emphasis, or contrast, especially if the speaker wants to stress I.

الان means now / right now.

In this sentence, it comes near the beginning:

من الان نمی‌توانم...
= I can’t ... right now

That is a very natural place for time words in Persian. Persian often puts words like now, today, tomorrow, etc. before the main verb phrase.

You may also hear slightly different placements depending on emphasis, but this position is very common.

نمی‌توانم breaks down like this:

• نـ / نه idea → negation, here as نمی
• می → imperfective/present marker
• توان → root related to being able
• ـم → I

So نمی‌توانم means I cannot / I’m not able to.

In standard spelling, it is usually written:

نمی‌توانم

with a نیم‌فاصله (half-space) after نمی.
But many people type it informally as:

نمیتوانم

Both are commonly seen, though نمی‌توانم is the more standard written form.

This is a very common Persian pattern.
صحبت کردن literally means to do conversation / to speak / to talk.

It is made of:

• صحبت = conversation, speech
• کردن = to do

So in the sentence:

با تو صحبت کنم
= talk with you

Persian uses many compound verbs like this, where a noun or verbal element combines with کردن, زدن, دادن, etc.

Examples:

• کار کردن = to work
• فکر کردن = to think
• تلفن کردن = to phone

So صحبت کردن is just the normal verb for to talk / to speak.

Here, با means with, so:

با تو = with you

That is the natural preposition with صحبت کردن when you mean talk to / talk with someone.

Even though English often says talk to you, Persian commonly uses with:

با تو صحبت کنم
literally: talk with you

So yes, با often means with, and in this sentence it is exactly the preposition needed.

تو is the informal singular you.
شما is the formal singular you, and also the plural you.

So:

• با تو صحبت کنم = talk to you (informal, one person)
• با شما صحبت کنم = talk to you (formal, or plural)

The choice depends on the relationship:

• تو for friends, family, close people, children
• شما for politeness, strangers, elders, formal situations

So this sentence sounds casual and familiar.

چون means because.

It introduces the reason:

من الان نمی‌توانم با تو صحبت کنم، چون دارم به مادرم زنگ می‌زنم.
= I can’t talk to you right now, because I’m calling my mother.

This is a very common way to connect two clauses in Persian.

You may also see چون که, but plain چون is very common and natural.

This is the progressive form, used for actions happening right now.

In the sentence:

دارم به مادرم زنگ می‌زنم

you have:

• دارم = I have / I am (from داشتن)
• می‌زنم = I hit / I do / I ring here as part of the compound verb زنگ زدن

Together, دارم ... می‌زنم means:

I am calling / I am in the middle of calling

This pattern is common in spoken and modern Persian for the present progressive:

• دارم می‌روم = I’m going
• دارم می‌خوانم = I’m reading
• دارم کار می‌کنم = I’m working

So دارم helps show that the action is happening right now.

Yes, literally زنگ زدن means something like to ring or to make a ring/bell sound.

But in modern Persian, زنگ زدن is a very common way to say:

• to call
• to phone
• to ring someone up

So:

به مادرم زنگ می‌زنم
= I’m calling my mother

This is completely natural Persian.

You could also hear تلفن کردن, but زنگ زدن is extremely common in everyday speech.

With زنگ زدن, Persian usually marks the person being called with به.

So:

• به مادرم زنگ می‌زنم
• literally: I am ringing to my mother
• natural English: I am calling my mother

This is just how the verb works in Persian.

More examples:

• به دوستم زنگ زدم = I called my friend
• به او زنگ بزن = Call him/her

So به is required here before the person receiving the call.

مادرم means my mother.

It is made of:

• مادر = mother
• ـم = my

So:

• مادرم = my mother
• مادرت = your mother
• مادرش = his/her mother

This attached ending is a very common way to show possession in Persian.

Because مادرم is not the direct object here in Persian grammar.

In English, my mother is the direct object of call, but Persian structures this differently:

به مادرم زنگ می‌زنم

The person being called is introduced by به, so it is not marked with را.

You would expect را with a direct object, but not after a preposition like به.

So:

• مادرم را می‌بینم = I see my mother
• به مادرم زنگ می‌زنم = I call my mother

Different verb pattern, different grammar.

Yes. Persian normally places the verb at or near the end of the clause.

So:

من الان نمی‌توانم با تو صحبت کنم

comes in this order:

• من = I
• الان = now
• نمی‌توانم = cannot
• با تو = with you
• صحبت کنم = talk

Even though نمی‌توانم appears earlier, the main verbal idea صحبت کنم still comes at the end. This is normal in Persian, especially with modal-like verbs such as توانستن.

So Persian often feels more verb-final than English.

Because after توانستن (can / be able to), Persian usually uses a subjunctive-style form.

So:

• می‌توانم صحبت کنم = I can talk
• نمی‌توانم صحبت کنم = I can’t talk

The form کنم here is the expected form after توانستن.

You would not normally say:

نمی‌توانم صحبت می‌کنم

because that combines structures in a way Persian does not usually allow.

So after can / cannot, use:

• بروم = go
• بخوانم = read
• صحبت کنم = talk

It is mostly conversational and very natural.

Reasons:

• تو is informal
• الان is common everyday speech
• دارم ... می‌زنم is natural spoken-style progressive
• زنگ زدن is a very common everyday way to say call

It is not slang, though. It is still normal standard Persian, just casual in tone because of تو and the everyday vocabulary.

The main change would be تو → شما.

So you could say:

من الان نمی‌توانم با شما صحبت کنم، چون دارم به مادرم زنگ می‌زنم.

That means:

I can’t talk to you right now, because I’m calling my mother.

If you want, you could also omit من:

الان نمی‌توانم با شما صحبت کنم، چون دارم به مادرم زنگ می‌زنم.

That sounds very natural too.

A natural pronunciation would be roughly:

man al-ān ne-mi-tu-nam bâ to soh-bat ko-nam, chun dâ-ram be mâ-da-ram zang mi-za-nam

A few notes:

• نمی‌توانم is often pronounced close to nemitunam in everyday speech.
• می‌زنم sounds like mizanam.
• چون sounds like chun.
• صحبت is usually pronounced sohbat.

So in casual romanization, many learners hear the sentence as:

man alan nemitunam ba to sohbat konam, chun daram be madaram zang mizanam

That is a helpful pronunciation guide, even though Persian spelling is different.

Yes, absolutely.

You could say:

من الان نمی‌توانم با تو صحبت کنم، چون به مادرم زنگ می‌زنم.

This can still mean because I’m calling my mother, especially from context.

Adding دارم makes the ongoing, right-now sense more explicit:

• زنگ می‌زنم = I call / I am calling
• دارم زنگ می‌زنم = I am calling right now

So دارم adds extra immediacy, but the sentence works without it too.