1(855)291-6640 is a fake "Hotmail Support Team" customer service telephone number. The fake support number is being used by cybercriminals to trick potential victims into calling it. If potential victims call the number, the cybercriminals will ask them for their Microsoft account credentials(usernames and passwords). If the requested information is given to the cybercriminals, they will use it to gain access to their potential victims' account, hijack and use them fraudulently.
The cybercriminals may even ask their potential victims to give them remote access to their computers. If they do so, the cybercriminals will secretly steal their personal or even financial information from their computers. Or, silently use their computers to commit other cybercrimes.
A Fake "Hotmail Support Team" Email
From: jenettecowles@confirmedsite.club <jenettecowles@confirmedsite.club>
Sent: February 28, 2018 4:54 AM
Subject: Your Account Has Been Hacked Call Now
You need to call now 1 855-291-6640
We Have Detected Unusual Activity With Your Hotmail Account and suspicious activity on your computer
Login Has Occurred on 2/27/2018 @ 12:51 PM EST
From IP: 33.124.12.1 Geo Location Found: Eastern Russia
If This Was Not You Please Call Hotmail Support Team
1 855-291-6640
Online users who have already called the fake technical support number and who have been tricked by the cybercriminals are asked to change their passwords immediately before their accounts are hijacked and used fraudulently.