Learn Spanish (Latin America): Cuando saturan la extensión, siempre insultan por el auricular. - When they overload the extension, they always insult over the headset.

This is the impersonal third-person plural. Even without a specific subject, Spanish uses the "they" form to talk about an unspecified group of people—in this context, likely angry callers or customers. It works exactly like the general "they" in English sentences like "they say it's going to rain."

Why is por used in por el auricular instead of en or sobre?

Por is used to indicate the means or medium of communication. Whenever you talk about speaking over the phone (por teléfono), on the radio (por radio), or through a headset (por el auricular), you must use por.

What does saturan la extensión actually mean in a real-world context?

In an office or call center environment, an extensión refers to a telephone line or extension number. The verb saturar means to saturate or overwhelm. Therefore, this phrase refers to flooding the phone lines with too many calls.

Is it correct to use insultan without specifying who is being insulted?

Yes! While insultar often takes a direct object pronoun to show who is receiving the abuse (like me insultan for "they insult me"), it can be used on its own to describe the general act of swearing or throwing insults.