3900 5851 — Spam Report / 垃圾電話報告

About this number / 關於此號碼

3900 5851 often repeats rambling calls that still try to extend the conversation, which is why many users read it as a non-core category caller that still feels intrusive. In the available reports, 3900 5851 usually focuses on 問卷調查 related promotions or checks. Even if the caller knows part of your information, it is safer not to commit during the call.

社群回報顯示 3900 5851 多以以禮品、折扣或會員福利作招徠作招徠，屬常見的非主要分類滋擾來電。 回報資料中，3900 5851 的目的多與 問卷調查 推廣或核實有關。 即使對方能說出部分個人資料，也不應在通話中立即作出承諾。

What to do / 應對方法

Do not return calls to unknown numbers. If you did not expect this call, it is best to ignore it. You can block this number on your phone.
不要回撥陌生號碼。如果你沒有預期此來電，最好忽略它。你可以在手機上封鎖此號碼。

How to block / 如何封鎖

iPhone: Settings → Phone → Blocked Contacts → Add New.
Android: Recent Calls → tap the number → Block / Report spam.