أتكلم مع صديقي عبر الهاتف.

Because in Arabic, the verb itself often already shows the subject.

• أتكلم means I speak / I am speaking
• The prefix أ- on the verb marks first person singular: I

So Arabic usually does not need أنا here.
You could say أنا أتكلم مع صديقي عبر الهاتف if you want extra emphasis, but normally أتكلم by itself already tells you the subject.

It is the present/imperfect form.

In Modern Standard Arabic, this form can cover several English ideas depending on context, including:

• I speak
• I am speaking
• I do speak

So أتكلم does not force just one English tense. The exact meaning depends on the situation.

The verb comes from the root ك ل م, which is related to speaking.

The dictionary form is usually given as تكلّمَ = to speak / to talk.
Then أتكلم is the I form in the present:

• تكلّمَ = he spoke / to speak
• أتكلم = I speak / I am speaking

This verb is from a derived verb pattern, and the doubled middle consonant is important in pronunciation.

A helpful pronunciation is:

a-ta-kal-lam

Points to notice:

• أ = a short a
• ت = t
• ك = k
• لّ has a shadda, so the l is doubled: kal-lam, not just ka-lam

So do not pronounce it like atakalam with only one l. The doubled l matters.

مع means with.

So:

• أتكلم مع صديقي = I speak with my friend

It is the normal preposition used for speaking with someone.

Because صديقي means my friend.

Breakdown:

• صديق = friend
• صديقي = my friend

The ending -ي is the possessive suffix meaning my.

So the sentence says with my friend, not just with a friend or with the friend.

Because it already becomes definite through possession.

• صديق = a friend / friend
• صديقي = my friend

In Arabic, a noun with a possessive suffix like -ي is already definite, so you do not add الـ.

So الصديقي would be wrong here.

The -ي here is primarily the possessive suffix meaning my.

So:

• صديق = friend
• صديقي = my friend

For a learner, the simplest way to understand it is: the final -ī is part of my friend.

More advanced note: when a noun has the my suffix (ياء المتكلم), normal case endings do not appear in the usual way, so you often just see the form صديقي.

عبر means via, through, or by way of.

So:

• عبر الهاتف = via the telephone / over the phone

It is a common formal way in MSA to express communication by means of something.

Both can be possible, but they are not exactly identical in feel.

• عبر الهاتف = via / over the phone
• بالهاتف = by telephone / by phone

In Modern Standard Arabic, عبر الهاتف often sounds a bit more formal or journalistic.
So this sentence is very natural in MSA.

Because Arabic often uses the definite article in expressions where English may use a more general noun.

Here:

• الهاتف = the telephone / the phone
• عبر الهاتف is a set phrase meaning by phone / over the phone

So even though English often says by phone without the, Arabic naturally says عبر الهاتف.

Yes, that is the usual way to understand it.

Since عبر functions as a preposition here, the following noun is in the genitive:

• عبر الهاتف

In normal everyday writing, short case vowels are usually not written, so you just see الهاتف.

Yes. Arabic allows some flexibility.

This sentence starts with the verb:

• أتكلم مع صديقي عبر الهاتف

This is a very natural Arabic pattern: verb + other parts of the sentence.

You could also say:

• أنا أتكلم مع صديقي عبر الهاتف

That adds the pronoun أنا for emphasis.

Not exactly.

• أتكلم = I speak / I talk
• أقول = I say

So in this sentence, أتكلم is correct because the idea is speaking/talking with someone.

You would not normally use أقول مع صديقي for this meaning.

Yes, a big difference.

• مع صديقي = with my friend
• إلى صديقي = to my friend

So:

• أتكلم مع صديقي = I speak with my friend
• أتكلم إلى صديقي = I speak to my friend

Both can be possible in some contexts, but مع emphasizes a conversation or interaction, which fits this sentence well.

It sounds natural and standard in Modern Standard Arabic.

Especially:

• أتكلم is standard
• عبر الهاتف sounds formal-neutral and very typical of MSA

In many spoken dialects, people might choose different wording, but for MSA this sentence is perfectly good.