Bei unbegrenztem Datenvolumen drosselt der Netzbetreiber die Geschwindigkeit nicht.

Here bei means something like with, in the case of, or when it comes to.

So bei unbegrenztem Datenvolumen means:

• with unlimited data
• in the case of unlimited data plans
• when the data allowance is unlimited

This is a very common use of bei in German. It does not always mean physical location like at or near.

Examples:

• Bei Regen bleiben wir zu Hause. = When it rains, we stay home.
• Bei Kindern muss man geduldig sein. = With children, you have to be patient.

So in this sentence, bei introduces the condition under which the rest is true.

Because bei always takes the dative case, and Datenvolumen is a neuter noun: das Datenvolumen.

The phrase is really:

• bei + dem unbegrenzten Datenvolumen

But because there is no article here, the adjective has to show the case ending itself. That is why you get:

• bei unbegrenztem Datenvolumen

This is the dative singular neuter adjective ending after no article.

A quick comparison:

• das unbegrenzte Datenvolumen → nominative
• bei unbegrenztem Datenvolumen → dative after bei

Das Datenvolumen is the amount of mobile data included in a phone or internet plan.

In English, depending on context, you might say:

• data allowance
• data volume
• mobile data limit

So unbegrenztes Datenvolumen means unlimited data.

German often uses compound nouns, and this is one of them:

• Daten = data
• Volumen = volume/amount

Together: Datenvolumen.

Drosseln means to throttle, to reduce, or to limit.

In the context of internet or mobile service, it usually means reducing the speed after a certain usage limit.

So:

• der Netzbetreiber drosselt die Geschwindigkeit = the network operator throttles the speed

This is a common technical/telecom verb in German.

Related forms:

• drosseln = infinitive
• drosselt = he/she/it throttles
• gedrosselt = throttled

German main clauses follow the verb-second rule. The conjugated verb must come in the second position.

Here the sentence begins with the phrase:

• Bei unbegrenztem Datenvolumen

That whole phrase counts as the first element. So the finite verb must come next:

• Bei unbegrenztem Datenvolumen | drosselt | der Netzbetreiber die Geschwindigkeit nicht.

If you started with the subject instead, you could also say:

• Der Netzbetreiber drosselt bei unbegrenztem Datenvolumen die Geschwindigkeit nicht.

That is also grammatically correct, just with a different emphasis.

Because Netzbetreiber is the subject of the sentence, and subjects are normally in the nominative case.

The noun is:

• der Netzbetreiber = the network operator/provider

So here:

• der Netzbetreiber = nominative subject
• die Geschwindigkeit = accusative object

A learner may notice that der can mean several things in German, but here it is simply the masculine nominative singular article.

Because Geschwindigkeit is a feminine noun:

• die Geschwindigkeit = the speed

It is also the direct object of drosseln, since it is the thing being reduced.

So the structure is:

• der Netzbetreiber = subject
• drosselt = verb
• die Geschwindigkeit = direct object
• nicht = negation

You can think of it as: The network operator does not reduce the speed.

In German, nicht usually comes before the part of the sentence it negates, and it often appears near the end of the clause when it negates the whole verb idea.

Here:

• ... drosselt der Netzbetreiber die Geschwindigkeit nicht.

This means the action of throttling does not happen.

German often places nicht after objects and other complements when the whole predicate is being negated.

Compare:

• Ich kenne ihn nicht. = I do not know him.
• Sie kauft das Buch nicht. = She is not buying the book.

So the position of nicht here is very normal.

Because kein is used to negate nouns, while nicht is used to negate verbs, adjectives, whole clauses, and many other sentence elements.

Here we are negating the action drosselt:

• Der Netzbetreiber drosselt ... nicht.

So nicht is the correct choice.

You would use kein with a noun phrase, for example:

• Der Netzbetreiber hat kein unbegrenztes Datenvolumen. = The provider has no unlimited data plan.

Not exactly, but it is close.

Der Netzbetreiber literally means network operator. In many real-world contexts, that can refer to the phone company or carrier operating the network.

Depending on context, English translations could be:

• network operator
• carrier
• provider

But Netzbetreiber emphasizes the operator of the network itself. In some situations, Anbieter would be a more general word for provider.

Yes. It is basically a compact noun phrase.

A fuller version could be something like:

• bei einem unbegrenzten Datenvolumen
• wenn das Datenvolumen unbegrenzt ist

These mean roughly the same thing, but the original sentence is more concise and sounds natural in formal or informational German.

So learners should know that German often prefers this kind of compact structure:

• bei + dative noun phrase

instead of always using a full when clause.

Yes. German allows some flexibility, as long as the verb-second rule is respected in a main clause.

For example, these are possible:

• Der Netzbetreiber drosselt bei unbegrenztem Datenvolumen die Geschwindigkeit nicht.
• Die Geschwindigkeit drosselt der Netzbetreiber bei unbegrenztem Datenvolumen nicht.

The original version puts the condition first:

• Bei unbegrenztem Datenvolumen drosselt der Netzbetreiber die Geschwindigkeit nicht.

That sounds natural if the speaker wants to emphasize the condition with unlimited data.

Yes, in this context it clearly refers to internet or data speed.

By itself, Geschwindigkeit just means speed, and it can be used in many contexts:

• car speed
• walking speed
• processing speed
• internet speed

But because the sentence talks about Datenvolumen and a Netzbetreiber, the meaning is clearly data speed or internet speed.

In German, it is very common to leave that implicit when the context makes it obvious.