The telephone number 855-203-6080 is currently being used by cybercriminals to trick Yahoo users into calling it. If potential victims call the same telephone number they will be asked for their email account credentials (usernames and passwords) and may also be asked for credit card and other sensitive information. And, once the cybercriminals have gotten their victims' account and personal information, they will use it to hijack their accounts and use them fraudulently.
A Sample of a Fraudulent Email Asking to Call 855-203-6080
From: "EMAIL SECURITY" <01718039.DCC9B9557CD39E4F7449D1agtdddhkkui@shleevqaxge.com>
Date: November 15, 2017 at 12:36:56 PM EST
Subject: Account Cancelation
We Have Detected Unusual Activity With Your Yahoo Account
Login Has Occurred On 11/10/2017 @ 9:38 AM
From IP: 34.26.95.326 Geo: Eastern Russia
If This Was Not You Please Call the Email Security Department
855-203-6080
Yahoo users who have already received the phishing email messages, and who have followed the instructions in them, are asked to change their Yahoo account passwords immediately before their accounts are hijacked by cybercriminals and used fraudulently. And, if they gave out their credit card information, they asked to contact their bank for help. They should let their banks know that they were tricked by a phishing email and unknowingly gave their credit card information to cybercriminals.