ग्राहक सेवा न केवल मोबाइल नंबर, बल्कि ओटीपी भी देखती है।

This is a very common Hindi pairing meaning not only ... but also ...

So in:

ग्राहक सेवा न केवल मोबाइल नंबर, बल्कि ओटीपी भी देखती है।

the structure is:

• न केवल = not only
• बल्कि = but rather / but also
• भी = also, too

Together, they connect two things being included:

• मोबाइल नंबर
• ओटीपी

A very natural way to understand the structure is:

Customer service looks at not only the mobile number, but also the OTP.

Hindi often uses all three pieces in this pattern, even though in English we may not think about them separately.

Because the subject ग्राहक सेवा is grammatically feminine singular.

The key noun here is सेवा, which is feminine in Hindi. Since the verb is agreeing with the subject, it appears as:

• देखती है = feminine singular
• not देखता है = masculine singular

So even though ग्राहक is often associated with a person and may feel masculine to an English speaker, the full expression ग्राहक सेवा is centered on सेवा, and सेवा is feminine.

That is why:

• ग्राहक सेवा देखती है = correct
• ग्राहक सेवा देखता है = not correct here

Because in Hindi, the verb normally agrees with the subject, not with the objects.

Here:

• ग्राहक सेवा = subject
• मोबाइल नंबर and ओटीपी = objects

Since the subject is singular and feminine, the verb stays singular feminine:

• देखती है

Even though two objects are mentioned, that does not make the verb plural.

Literally, देखना means to see / to look at.

But in many real contexts, especially administrative or technical ones, देखना can mean things like:

• check
• look at
• review
• view
• verify (depending on context)

So here, देखती है probably does not mean simple visual seeing. It more likely means something like:

• customer service checks
• customer service looks at
• customer service can view

This is a very common feature of Hindi: a basic verb like देखना can cover several English verbs depending on context.

Because not every direct object in Hindi needs को.

With verbs like देखना, the object is often used without को, especially when the object is:

• inanimate
• general
• non-specific in a broad sense
• treated as information or content

So:

• मोबाइल नंबर देखती है
• ओटीपी देखती है

is completely normal.

You can sometimes see को with direct objects in other contexts, especially when the object is specific, animate, or marked for emphasis, but here zero marking is the normal choice.

Because भी usually comes right after the word or phrase it is focusing on.

Here:

• ओटीपी भी = the OTP too / also the OTP

So the sentence highlights that customer service sees:

• not only the mobile number
• but the OTP as well

Placing भी after ओटीपी is the natural way to mark OTP as the additional item.

If you move भी, the emphasis can change or the sentence may sound less natural.

No, the comma is not grammatically necessary in Hindi.

Hindi punctuation is often lighter and less rigid than English punctuation, especially in everyday writing. The comma here simply helps the reader see the contrast structure:

• न केवल मोबाइल नंबर
• बल्कि ओटीपी भी

So this would also be fine:

ग्राहक सेवा न केवल मोबाइल नंबर बल्कि ओटीपी भी देखती है।

The comma is mainly a readability choice.

They are examples of words commonly used in Hindi that come from English or modern technical vocabulary.

This is extremely common in present-day Hindi, especially in areas like:

• technology
• banking
• customer support
• phones
• websites
• apps

So learners should get used to seeing Hindi sentences that contain words like:

• मोबाइल
• नंबर
• ओटीपी
• लॉगिन
• पासवर्ड

These words are often written in Devanagari but behave like everyday Hindi vocabulary in actual use.

Yes. That is another very common way to express not only ... but also ...

For example:

ग्राहक सेवा सिर्फ़ मोबाइल नंबर ही नहीं, बल्कि ओटीपी भी देखती है।

or

ग्राहक सेवा मोबाइल नंबर ही नहीं, बल्कि ओटीपी भी देखती है।

This pattern is very close in meaning to न केवल ... बल्कि ... भी.

A rough comparison:

• न केवल ... बल्कि ... भी = a bit more formal
• ही नहीं ... बल्कि ... भी = very common and natural
• सिर्फ़ ... नहीं ... बल्कि ... भी = also common

So the sentence you were given is correct and natural, but it is not the only way to express the idea.

Hindi word order is flexible, but some orders sound more natural than others.

The given sentence is very natural:

ग्राहक सेवा न केवल मोबाइल नंबर, बल्कि ओटीपी भी देखती है।

A more tightly connected version many speakers might also use is:

ग्राहक सेवा न केवल मोबाइल नंबर बल्कि ओटीपी भी देखती है।

Another common alternative is:

ग्राहक सेवा मोबाइल नंबर ही नहीं, बल्कि ओटीपी भी देखती है।

So yes, Hindi allows some movement, but the paired expressions:

• न केवल ... बल्कि ... भी
• ही नहीं ... बल्कि ... भी

should stay clearly matched so the sentence is easy to follow.

It usually means customer service as a service, team, or department.

Grammatically, it behaves like a singular noun phrase. So Hindi treats it as one unit:

• ग्राहक = customer
• सेवा = service

Together:

• ग्राहक सेवा = customer service

Even if in real life many people may work in customer service, the phrase itself is grammatically singular here, which is why the sentence uses singular feminine agreement:

• देखती है

You might occasionally hear a shortened version in casual speech, but in this structure भी is normally expected.

The full standard pattern is:

• न केवल X, बल्कि Y भी

Without भी, the sentence may still be understandable, but it sounds less complete and less balanced.

So for learners, it is best to remember the pattern as a set:

• न केवल ... बल्कि ... भी

Because Hindi, like English, usually does not need to repeat the verb when one verb applies to multiple objects.

So instead of saying something like:

• customer service sees the mobile number and sees the OTP

Hindi naturally says:

• ग्राहक सेवा न केवल मोबाइल नंबर, बल्कि ओटीपी भी देखती है।

One verb at the end covers both objects. This is very normal Hindi sentence structure.