Số điện thoại đăng ký này đúng không?

A natural breakdown is:

• số điện thoại = phone number
• đăng ký = register / registered / registration
• này = this
• đúng = correct
• không = no / not, but in this pattern it helps form a yes-no confirmation question

So the structure is roughly:

• Số điện thoại đăng ký này = this registered phone number / this phone number for registration
• đúng không? = is it correct?

The whole sentence is asking for confirmation.

In Vietnamese, modifiers often come after the noun they describe.

So:

• số điện thoại đăng ký = the phone number used for registration / the registered phone number

This is different from English, where we usually put the modifier before the noun:

• registered phone number

Vietnamese often uses a verb-like word after the noun to describe it. That is very normal.

It can feel like either, depending on how you analyze it.

Vietnamese words do not change form the way English words do, so đăng ký can function in different ways depending on context. Here it works like a modifier for số điện thoại and is understood as something like:

• the phone number used to register
• the registered phone number
• the phone number on file for registration

So even though đăng ký is basically the verb to register, in this sentence it behaves more like registered / for registration in English.

In Vietnamese, demonstratives like này (this) usually come after the noun.

So:

• số điện thoại này = this phone number

And with a longer noun phrase:

• số điện thoại đăng ký này = this registered phone number

That is normal Vietnamese word order. English says this phone number, but Vietnamese says something closer to phone number this.

It refers to the whole noun phrase.

So số điện thoại đăng ký này means:

• this registered phone number not
• this phone number, which registers something

In other words, này points to the full thing being discussed: the specific phone number connected with registration.

Đúng không? is a very common Vietnamese way to ask for confirmation. It is like:

• Is that correct?
• Right?
• Correct, or not?

Literally, it is:

• đúng = correct
• không = not

So the pattern is basically:

• X đúng không? = Is X correct?

This is extremely common in everyday speech.

Vietnamese often does not need a copula like English is/are in sentences with adjectives.

In English:

• This phone number is correct.

In Vietnamese:

• Số điện thoại này đúng.

There is no separate word required for is here. The adjective đúng can directly describe the subject.

So in the question:

• Số điện thoại đăng ký này đúng không? literally works like:
• This registered phone number correct not?

That is normal Vietnamese grammar.

Yes, you often can.

For example:

• Số điện thoại đăng ký này có đúng không?

This also means Is this registered phone number correct?

Adding có can make the yes-no question pattern feel more explicit. In everyday speech, both versions are possible, though the version without có is also very natural.

They are similar, but not exactly identical in tone.

• đúng không? = correct or not? / right?
• phải không? = is that right? / isn’t that so?
• đúng chứ? = right? / surely that’s right, yes?

Very roughly:

• đúng không is neutral and common
• phải không is also common and natural for confirmation
• đúng chứ can sound a bit more expectant, as if the speaker thinks the answer should be yes

So they are close, but not always perfectly interchangeable in tone.

It is asking whether the phone number is the correct one.

That is, the thing being checked is:

• the phone number connected with registration

It does not normally mean:

• Was the act of registering done correctly?

If you wanted to ask whether the registration process was correct, you would usually phrase it differently.

No, that version would sound different and could be confusing.

• Số điện thoại đăng ký này đúng không? = Is this registered phone number correct?
• Số điện thoại này đăng ký đúng không? sounds more like Was this phone number registered correctly? or Does this phone number register correctly?, depending on context

The position of đăng ký matters a lot. In the original sentence, đăng ký modifies số điện thoại. In the changed version, it starts to sound more verbal.

Common answers would be:

• Đúng. = Correct.
• Đúng rồi. = Yes, that’s right.
• Vâng, đúng ạ. = Yes, that’s correct.
• Không. = No.
• Không đúng. = Not correct.
• Không phải số này. = It’s not this number.

If you are speaking politely, especially to a customer or older person, you might add ạ:

• Dạ, đúng ạ.
• Dạ, không đúng ạ.

Yes, it is natural, especially in situations like checking information.

For example, a staff member might ask:

• Số điện thoại đăng ký này đúng không ạ?

Adding ạ makes it more polite and professional.

Without ạ, the sentence is still correct, but it sounds more neutral and less formal.

Yes, that is a useful way to remember it, but in actual English the smoother meaning is usually:

• the phone number used for registration
• the registered phone number
• the phone number on the account

So registration phone number may help you understand the structure, but it is not always the best final translation.

A simple way to see it is:

• [noun phrase] + đúng không?

Here:

• [noun phrase] = Số điện thoại đăng ký này
• đúng không? = is it correct?

So the sentence structure is basically:

• This registered phone number — correct or not?

That is a very common Vietnamese way to form a confirmation question.