SIM-картка в телефоні.

Because Ukrainian usually omits the present-tense verb to be.

So:

• SIM-картка в телефоні literally looks like SIM card in phone
• but it naturally means The SIM card is in the phone

This is very normal in Ukrainian.
If you wanted a version closer to There is a SIM card in the phone, you could say У телефоні є SIM-картка.

Because after в or у when you mean location (in, inside), Ukrainian uses the locative case.

• dictionary form: телефон
• after в/у for location: в телефоні / у телефоні

So в телефоні means in the phone.

Yes. у телефоні and в телефоні mean the same thing here.

Ukrainian often alternates у and в for euphony — basically, to make the sentence sound smoother. The choice usually depends on the surrounding sounds, not on a change in meaning.

So both are correct:

• SIM-картка в телефоні
• SIM-картка у телефоні

Because a SIM card is inside the phone, not on it.

• в телефоні = in the phone
• на телефоні would usually suggest on the phone physically, or sometimes something connected with phone use, but not inside the device

For a SIM card, в телефоні is the natural choice.

It is a feminine singular noun phrase meaning SIM card.

The second part, картка, is a feminine noun meaning card, and the whole compound behaves like a feminine noun. In this sentence it is in the nominative singular, because it is the main noun of the sentence.

So:

• SIM-картка = nominative singular
• feminine noun

Because this is a common Ukrainian way to write a compound made from:

• an abbreviation or acronym: SIM
• plus a noun: картка

So SIM-картка is the standard written form.

In everyday speech, many speakers pronounce it like сім-картка.

So even though it is often written with Latin letters as SIM-картка, it is usually said as one syllable for SIM, not spelled out letter by letter in English.

It can work as a complete sentence in Ukrainian because the present-tense is is understood.

So it is perfectly normal as a sentence meaning The SIM card is in the phone.

At the same time, depending on context, it could also look like a short label or caption. Ukrainian allows that kind of compact structure very naturally.

Yes. Ukrainian word order is fairly flexible, and changing it often changes emphasis rather than basic meaning.

For example:

• SIM-картка в телефоні = neutral, straightforward
• У телефоні є SIM-картка = more like There is a SIM card in the phone
• В телефоні SIM-картка = possible, but the emphasis shifts

So the original order is natural, but it is not the only possible one.

Because Ukrainian does not have articles like English a/an/the.

So SIM-картка can mean:

• a SIM card
• the SIM card

Which one is intended depends on the context.