Learn Hardcore Russian: Иногда сосед звонит мне вечером. - Sometimes the neighbor calls me in the evening.

Иногда means “sometimes.” It’s an adverb of frequency, so starting the sentence with Иногда highlights that the action occurs only occasionally. You can also move it elsewhere (e.g., Сосед мне иногда звонит вечером) without changing the core meaning.

How do I know that сосед is the subject of the sentence and why is it in the nominative case?

The subject—the one performing the action—is always in the nominative case in Russian. Here, сосед (“neighbor”) does the calling, so it appears in the nominative singular form.

Why is мне in the dative case rather than the accusative case?

The verb звонить (to call on the phone) takes the person being called in the dative case. In Russian you “ring to someone,” so you say звонить + дательный падеж. Hence, мне (“to me”) is dative, not accusative.

What is the function of вечером in this sentence and why is it in the instrumental case?

Time‑of‑day words like утром, днём, вечером typically use the instrumental case to mean “at [that part of the day].” So вечером here answers “when” the calling happens: “in the evening.”

Could I say instead of ? What’s the difference?