Darn, it's out of stock
(for now)
Galaxy S21 Ultra 5G 512GB - Black - Locked AT&T

Galaxy S21 Ultra 5G 512GB - Black - Locked AT&T

is currently unavailable.

All devices are restored professionally based on a 25-point inspection

  • Buttons
  • SIM and/or memory card reader
  • Data deletion
  • Chargers and/or cables
  • Unlocking
  • GPS and/or positioning system
  • Cameras
  • External sensors
  • Biometric sensors
  • WiFi and Bluetooth
  • IMEI serial number
  • Oxidation
  • Flash and indicator lights
  • Mics and speakers
  • Input and output ports
  • Phone carrier
  • Battery health
  • Mechanical parts
  • Parts compatibility
  • Screen
  • Other features specific to this device

Galaxy S21 Ultra 5G 512GB - Black - Locked AT&T's customer reviews

19 verified reviews in the last 24 months.

  • D

    Debbie L.

    Purchased on October 31, 2024

    Verified purchase

    Phone is perfect for me! So glad I could buy an ATT refurb, since some features are not available on unlocked devices. Replaced the same phone I had, an unlocked S21 Ultra with a cracked screen which would cost more to fix than this refurb, and since ATT service/reception has been going steadily downhill, really appreciate that I can use WiFi calling now. Yeah, I should switch but no guarantee that service would be any better. Totally happy with this purchase!

    Reviewed in the United States on March 26, 2025

  • E

    Eric H.

    Purchased on February 18, 2024

    Verified purchase

    This is my 3rd purchase from backmartket and I must say, they have never failed to deliver a quality product to me! This phone is in amazing condition it has 1 tiny little scuff on the screen that was maybe ⅛ of an inch long that was super shallow and completely disappeared when I put a screen protector on it!everything else works perfectly and it is a major improvement from my s10 thank your again backmartket I've recommended you to everyone that's said they needed a new phone and plan on purchasing all my tech from you in the foreseeable future if possible

    Reviewed in the United States on March 26, 2025

  • M

    Mason H.

    Purchased on October 15, 2024

    Verified purchase

    The condition was near perfect though it had minor screen burn in only noticeable if you really look into it

    Reviewed in the United States on March 26, 2025

  • R

    Renee L.

    Purchased on August 8, 2023

    Verified purchase

    I was honestly worried getting a used phone. But I wasn't paying 1000 for a phone. so I went back and worth for couple weeks and I had message company and asked few questions. They was awesome and answered all my questions. so I ordered the phone I wanted and it was here in 3 days. let me tell you. This phone looks brand new. I have had it for couple days and no problems at all. I absolutely love it. I will be buying more stuff from here.

    Reviewed in the United States on March 26, 2025

  • J

    Jennifer K.

    Purchased on May 2, 2023

    Verified purchase

    It looks brand new! I've had my S21 Ultra a few weeks now and I absolutely LOVE IT. It arrived really fast, only a few days after purchase. Back market emailed me throughout and after the process making sure I am happy. This will NOT be my last purchase! Thanks!!!

    Reviewed in the United States on March 26, 2025

  • J

    Jesse V.

    Purchased on February 26, 2024

    Verified purchase

    fast delivery phone as it should be fast trade in payout 3rd time using back market!! never go back! Great savings love it!!

    Reviewed in the United States on March 26, 2025

  • C

    Charles H.

    Purchased on February 27, 2024

    Verified purchase

    just received my phone yesterday and I would order again this place is great I will never buy a new phone again I will buy a used from back market

    Reviewed in the United States on March 26, 2025

See all 19 reviews

Reborn vs. brand new

Here’s what you help prevent on average by choosing a reborn smartphone over a brand new one.

171.1 lbs of CO2e

That's like driving an SUV from NYC to Chicago.

6.3 oz of e-waste

That’s around the weight of a baseball.

537.1 lbs of raw materials

That's like 20 dogs digging in your yard for a week.

20,341.2 gallons of water

That's like running a faucet for 3 days

Everything you ever wanted to know about the Galaxy S21 Ultra 5G 512GB - Black - Locked AT&T

  • BlackColor

  • 6.8Screen size (inches)

  • Galaxy S21 Ultra 5GModel

  • AndroidOS

  • 1440 x 3200Resolution

  • USB-CConnector

  • AT&TCarrier compatibility

  • 512 GBStorage

  • 16 GBMemory

Galaxy S21 Ultra 5G 512 GB - Phantom Black AT&T

Galaxy S21 Ultra 5G 512GB - Black - Locked AT&T
ColorBlack
Screen size (inches)6.8
ModelGalaxy S21 Ultra 5G
OSAndroid
Resolution1440 x 3200
ConnectorUSB-C
Carrier compatibilityAT&T
Storage512 GB
Memory16 GB
Screen typeDynamic AMOLED 2X
Network5G
Manufacturer Ref.SM-G998U
Memory Card SlotNo
Verizon compatibleNo
AT&T compatibleYes
T-Mobile compatibleNo
Release Year2021
Last OS CompatibilityYes
FoldableNo
Front camera40 megapixels
SAR head0.65
SAR body0.95
SeriesSamsung Galaxy S
SIM cardPhysical SIM + eSIM
Retro techNo
Main camera108 megapixels
Color (official name)Phantom Black
Company nameSamsung Electronics
Company email addresssupport@samsung.com
Company postal addressSamsung House, 1000 Hillswood Drive, Chertsey, Surrey, KT16 0PS, UK
BrandSamsung
Weight8 oz

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