Learn Hardcore Korean: bihaenggi aneseoneun jeonhwareul mos haeyo. - You can’t make phone calls on the plane.

비행기 안에 means “inside the airplane.”
-서 marks it as the location where the action happens (“at/in”).
-는 turns that whole phrase into a topic: “as for inside the plane…”
Without -는, you’d just state the place. With -는, you highlight or contrast it (e.g., inside vs. outside).
You could say 비행기에서는 (“on the plane”) or even 기내에서는 (more formal “in the cabin”), but 안에서는 emphasizes being physically inside.

Why is it 전화를 못 해요 instead of 전화 못 해요?

Korean requires the object-marking particle -를 (or -을) on definite objects. Here:

전화 (phone call) is the object of 하다 (“to do”), so you say 전화를 하다.
In polite present: 전화를 해요, and with inability: 전화를 못 해요.
Dropping -를 would sound ungrammatical.

What’s the difference between 못 해요 and 안 해요 in this context?

못 해요 expresses inability or not being allowed (“cannot”).
안 해요 simply means does not do (“won’t”).
On a plane, 못 해요 implies a rule or physical restriction; 안 해요 would sound like you’re just choosing not to call.

Why do we use 해요 here? Isn’t 전화하다 already one verb?

전화하다 is the dictionary form (“to call”).
In polite present tense, -하다 becomes -해요: 전화해요.
When you add an object, it becomes 전화를 하다, and in polite speech 전화를 해요.
Thus 전화를 못 해요 = “(I/you) can’t make a phone call.”

Could we use a different verb like 전화를 걸다 instead of 전화하다?

Yes. 전화를 걸다 literally “to hang a phone (i.e. place a call).” You might say:

비행기 안에서는 전화를 걸 수 없어요 (“You can’t place calls inside the plane.”)
Both 전화하다 and 전화를 걸다 are common.

Why is the sentence in the polite informal style (-해요) and not the formal -합니다?

-해요 (요-form) is the standard polite style in everyday conversation.
-합니다 is the formal/official style, often used in announcements:
“비행기 안에서는 전화를 못 합니다.”
On most flights you’ll hear the formal -합니다 from the crew.

Can I reorder the sentence, for example: 전화를 비행기 안에서는 못 해요?

Yes. Korean word order is flexible because particles show each word’s role.

비행기 안에서는 (topic) usually goes first, but you could also say 전화를 비행기 안에서는 못 해요 without changing the meaning.

Could we express a stronger prohibition, for example using 안 돼요?

Definitely. To say “you must not,” you could use -면 안 돼요:

비행기 안에서는 전화를 하면 안 돼요 (“You must not make calls inside the plane.”)
This is more direct “prohibition” than 못 해요, which is a softer “can’t.”

Is there any nuance between 비행기 안에서는 전화를 못 해요 and 기내에서는 전자 기기 사용이 제한됩니다?

기내에서는 전자 기기 사용이 제한됩니다 is a formal announcement style (“In the cabin, electronic device use is restricted”).
비행기 안에서는 전화를 못 해요 is colloquial and specific to phone calls.
The former is broader (all electronics) and more official; the latter is casual and focused.

How would I make this sentence past tense or future tense?

Past tense (couldn’t): 비행기 안에서는 전화를 못 했어요.
Future tense (will not be able to): 비행기 안에서는 전화를 못 할 거예요.
Just change 못 해요 → 못 했어요 (past) or 못 할 거예요 (future).