Learn Hardcore Japanese: watasi ha haha ni denwa wo kakemasu.

The topic is what the sentence is “about.” The grammatical subject of the verb かけます (call / make a call) is also 私, so in this sentence the topic and subject happen to be the same, but that’s not always true.

You could normally drop 私 and just say:

母に電話をかけます。
(The topic “I” is understood from context.)

Use 私は when:

You need to clarify that it’s you (not someone else).
You’re starting a new topic: As for me, I call my mother.

Why is it 母に and not 母を?

に marks the target / recipient of the action, similar to “to” in English.

母に電話をかけます。
= [I] make a phone call *to my mother.*

In this structure:

電話 (phone call) is the direct object → marked by を.
母 (mother) is the recipient of that phone call → marked by に.

If you said 母を電話をかけます, it would be ungrammatical. The verb 電話をかける always takes:

Xに電話をかける = call X
誰に電話をかけましたか。 = Who did you call?

Why do we say 電話をかけます instead of just a single verb?

Japanese often uses a noun + generic verb pattern.

電話 = phone / phone call
かける = to hang, to apply, to put on, etc. (a very general verb)

Together, 電話をかける literally feels like “to make/apply a phone call.”
That’s why 電話 takes を as if it were a separate object.

This is similar to English:

“make a phone call”
“take a walk”
“have a look”

Japanese does this a lot:

勉強する = to study (do study)
掃除をする = to clean (do cleaning)
質問をする = to ask a question (do a question)

What’s the difference between 電話をかける and 電話する?

Both can mean “to call (on the phone).”

母に電話をかけます。
母に電話します。

In everyday speech:

Both are correct and natural.
電話する is slightly shorter and more casual-feeling.
電話をかける can feel a bit more explicit or careful, but is also very common.

Most learners can treat them as near-synonyms:

Xに電話をかける ≒ Xに電話する = call X

Why is it かけます and not かける?

かけます is the polite -ます form of the verb かける.

Dictionary (plain) form: かける
Polite non-past: かけます

You use -ます:

With people you’re not close to
In most public / formal / classroom situations
In textbooks’ default examples

Casual versions:

母に電話をかける。 (Plain)
To friends/family you can use this instead of かけます.

Does かけます mean “call” right now or “will call” in the future?

Japanese non-past (かける / かけます) covers both:

Present / habitual:
毎週、母に電話をかけます。
I call my mother every week.
Future / planned:
あとで母に電話をかけます。
I will call my mother later.

The exact English tense (present vs future) depends on context words like あとで (later), 明日 (tomorrow), 毎日 (every day), etc.

Why is there no “my” before 母? How do I know it’s my mother?

In Japanese, when you talk about your own close family members to an outsider, you usually don’t add “my”. It’s assumed from context that you mean your own.

So:

母に電話をかけます。
→ normally understood as I (will) call my mother.

If you need to be explicit, you can say:

私の母に電話をかけます。 = I will call my mother.

But in most everyday contexts, 母 by itself is enough to be understood as my mother when you’re the speaker.

Should I say 母 or お母さん here?

It depends on whose mother and who you’re talking to.

Talking about your own mother to someone outside your family:
→ Use 母 (humble, no honorific).
母に電話をかけます。 is perfect.
Talking to your mother, or about her to family members:
→ You normally say お母さん.
E.g. to your sibling: お母さんに電話をかける？
Talking about someone else’s mother (showing respect):
→ Use お母さん (with さん).
田中さんのお母さんに電話をかけます。

So in the textbook-style neutral sentence, 母 usually means my mother and is appropriate.

Can I leave out 私は and just say 母に電話をかけます?

Yes, and in real conversation that’s actually more natural if the subject is obvious.

母に電話をかけます。
(Context: you’re talking about your own actions.)
→ Understood as I will call my mother.

You keep 私は when:

You want to contrast:
私は母に電話をかけますが、弟はメールしかしません。
I call my mother, but my younger brother only emails.
The subject might be ambiguous otherwise and you’re clarifying who does it.

Can I change the word order, like 母に私は電話をかけます?

Japanese word order is relatively flexible, but the verb must stay at the end.

Possible variants:

私は母に電話をかけます。 (very standard)
母に私は電話をかけます。 (grammatical, but slightly marked/emphatic)
母に電話をかけます。 (natural if subject is clear)

You cannot move the verb away from the end:

✗ 私は電話をかけます母に。 (wrong)

So you can shuffle the noun + particle parts for emphasis, but 電話をかけます must come at/near the end.

Why is は pronounced “wa” here and not “ha”?

The character は serves two roles:

As a syllable in words: it’s pronounced “ha”
- はな = hana
- はし = hashi
As the topic particle (as in 私は): it’s pronounced “wa”
- 私は = watashi wa
- 母は = haha wa

So は after 私 is not part of the word わたし; it’s the separate topic particle, which is read wa by convention.

Could I use が instead of は, like 私が母に電話をかけます? What’s the difference?

You can say 私が母に電話をかけます, but the nuance changes:

私は母に電話をかけます。
→ As for me, I call my mother.
Neutral statement; “I” is the topic.
私が母に電話をかけます。
→ I (and not someone else) will call my mother.
Emphasizes that I is the one who does it, often as an answer to “Who will call her?”

Example:

A: 誰が母に電話をかけますか。 (Who will call Mother?)
B: 私が母に電話をかけます。 (I will call her.)

So use が when you want to highlight / identify the doer; use は for a general topic.

Can I say 母へ電話をかけます instead of 母に? What’s the difference between に and へ here?

In this sentence, 母に is the most natural and standard.

に marks the recipient/target of the phone call.
へ mainly marks direction (towards a place or person) and is very common with letters, emails, messages:
- 母へ手紙を書きます。 = I write a letter to my mother.

母へ電話をかけます is not wrong, but sounds less usual; many native speakers would naturally say 母に電話をかけます. For phone calls, default to Xに電話(を)かける / Xに電話する.