iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
To block a known number on a Samsung Galaxy S21, open Phone, tap More options (the three dots) > Settings > Block numbers, enter the number, and tap Add. You can also block someone from Contacts or block a text conversation in Samsung Messages. Use the separate unknown-caller and spam controls for nuisance calls from numbers you do not recognize; blocking one number does not stop someone from calling or messaging from a different number.
This guide applies to the Galaxy S21, S21+, and S21 Ultra. The menu wording and availability can differ by wireless provider, software version, phone model, and whether you use Samsung or Google apps. Start with the route that matches the problem: a specific person, a text thread, private or unknown callers, or suspected spam from changing numbers.
What should I use to block calls, texts, or spam on my Galaxy S21?
Choose the control according to what you want to stop. A blocked phone number is the most direct option for a known caller; blocking a conversation in Samsung Messages addresses that messaging route; unknown-caller and spam controls cover different categories and may be carrier-dependent. These controls are not interchangeable, so decide whether the nuisance is a particular number, a message thread, or calls arriving from multiple unidentified numbers.
| Control | Scope | Channel | Typical outcome |
|---|---|---|---|
| Block a number or contact | A specific phone number or saved contact | Calls and messages associated with that number | Calls may be ignored or sent to voicemail; messages may not reach the Messages app |
| Block a conversation in Samsung Messages | A selected text conversation | Samsung Messages | Messages from that conversation are blocked |
| Block calls from unknown numbers | Unknown callers, subject to the Samsung/carrier feature’s meaning and availability | Calls | Calls are blocked according to the enabled phone control |
| Spam identification or carrier protection | Calls identified as spam, depending on the service | Calls | May warn about or filter suspected spam; the exact behavior depends on the available feature |
The practical distinction is scope, channel, and outcome. Direct blocking targets a number you know. A Messages block is useful when you want to manage a conversation in that app. Unknown-caller controls are broader, but their meaning depends on the app and carrier. Spam identification may warn about or filter calls that a service recognizes as suspicious; it is not the same as adding every nuisance caller to a personal block list.
Popular on Amazon
- 【90 Degree Full Function USB C Adapter】Supports the latest USB4 standard for up to 40Gbps of bandwidth, 8K video support, and up to 240W Fast charging; Support USB PD 3.1 Extended Power Range (EPR) including 140W, 180W and 240W. Your productivity is easily doubled. *Warm Tip: For the best fit, please make sure the USB-C port is fully exposed; thick or bulky cases may affect compatibility.
- 【Reliable Quality】Made from high-quality, scratch-resistant aluminum alloy, delicate metal frame. get excellent wear resistance and heat dissipation. Non-Slip Design for easier insertion and removal.
- 【Small and portable】Ultra thin size, ultra compact design, a petite physique that matches the minimalist design of your modern laptops. Coming with a slim figure that won't block the port next to the one it's plugged into.
- 【Compatibility】Widely work with most usb c, thunderbolt 4/3 devices. Compatibilit for ROG Ally, Steam Deck, Switch, MacBook Pro, Quest 3 VR headset, Surface Book 2, iPhone 18/17/16/15, Samsung Galaxy S23/S22/S21, Note 20/10, Google Pixel, ChromeBook, etc.
- 【Excellence Customer Support】If you experience any issues or cable failure, simply reach out to our dedicated customer service team. We provide a prompt response within 18 hours, providing you with the necessary technical support to resolve any concerns.
Samsung says feature availability can vary by wireless provider, software version, and phone model. Its Smart Call feature may be unavailable with some carriers, so a missing control does not necessarily mean the S21 is malfunctioning. Samsung’s Phone and Messages apps also have their own settings. If you use Google Phone or Google Messages, look for the equivalent controls in those apps rather than assuming every Samsung menu will be present.
How do I block a number on my Samsung S21?
For an unsaved number, use the Samsung Phone app’s blocked-number list. You can type the number or select one already recorded in Recents or Contacts. This is usually the simplest method when you already know which number you want to stop, and you do not need to create a contact first.
- Open Phone.
- Tap More options (three dots), then Settings.
- Tap Block numbers.
- Enter the phone number and tap Add. If the number is already in Recents or Contacts, select it and tap Done instead.
Check the digits before saving, especially if you are entering a number manually. A number-specific block is only as broad as the entry you add: it does not automatically cover other numbers used by the same caller. The list is also not a blanket setting for every caller whose number is not saved.
Recommended Free Tools
If the number is in your call history, choosing it from Recents or Contacts avoids retyping it. If you enter it manually, use the number as it appears for the caller, including the correct digits. Once added, you can return to Block numbers to check the entry or remove it later.
How do I block someone from Recents?
Open Phone > Recents, select the caller, tap Details > Block, and confirm. Depending on the software version, the call-list screen may let you select a recent number and block it directly. If the layout on your S21 differs, use the Phone app’s Settings > Block numbers route instead.
Use this method when you have just received an unwanted call and want to block the number shown in the call record. The recent-call route and the blocked-number list are two ways to reach the same basic number-blocking task; confirm the action if the phone asks you to do so.
Also popular on Amazon
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
How do I block a saved contact?
Open Contacts, select the person, tap More > Block contact, then confirm by tapping Block. The contact remains in your Contacts list; blocking does not delete it. Use this route when you recognize the person by name and want to select the saved contact rather than locate a number in your call history.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Blocking from Contacts is still about preventing contact through the blocked route, not removing the person from your address book. If you later want to allow contact again, you can use Unblock contact from that contact’s menu.
How do I stop someone from texting me on a Galaxy S21?
In Samsung Messages, block the unwanted conversation from the conversation list. This is a messaging control and is separate from blocking a caller through the Phone app.
- Open Messages and locate the conversation.
- Touch and hold the conversation.
- Tap More, then Block.
- Confirm the action when prompted.
To review or edit blocked entries, open Messages > More options > Settings > Block numbers and spam. If your S21 uses Google Messages rather than Samsung Messages, its labels and controls may differ.
Blocking a conversation is useful when the unwanted contact is a text thread you can identify in Samsung Messages. If you are trying to stop both calls and messages from a known number, consider the Phone app’s number-blocking option as well; the app-level route you choose matters. Conversely, if you only want to manage messages in Samsung Messages, its blocked-list settings are where you review that action.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →How do I block private or unknown callers on a Samsung S21?
In Samsung Phone, open Phone > More options > Settings > Block numbers, then turn on Block calls from unknown numbers if that option appears. Samsung describes this as a Smart Call-related control for unknown numbers not in Contacts, but availability and wording can vary by carrier and software.
Also popular on Amazon
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
Do not assume that “unknown” always means every number absent from your Contacts. Google’s Phone app documentation uses Unknown for private or unidentified callers; ordinary numbers that are not saved in Contacts are still allowed under that setting. If you use Google Phone instead of Samsung Phone, its setting and behavior may therefore differ from Samsung’s menu. Check the actual app and the wording shown on your S21 before enabling a broader rule.
For suspected spam from changing numbers, check whether your carrier offers call identification or spam filtering. Samsung notes that Smart Call is not available with certain carriers, and carrier protections are not identical across providers. A single-number block is still useful for a repeat caller using the same number; filtering or identification is the category to investigate when nuisance calls arrive under changing numbers.
These options have different consequences: number blocking aims at a specific entry, private/unknown caller blocking addresses calls in the category defined by that app, and spam tools rely on available identification or carrier features. There is no universal control in the documented S21 menus that guarantees every spam call will be stopped. Select the narrowest control that addresses the problem, and check your provider’s options if the built-in control is unavailable or not enough.
Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minutePC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11What happens after I block a number?
The blocked caller’s calls and messages are generally suppressed, but the precise call handling can depend on the carrier and software configuration. Verizon’s S21 support page says blocked calls are forwarded to voicemail and that text or picture messages are not delivered to the Messages app. The Samsung S21 user manual likewise describes future calls from a blocked number going directly to voicemail and messages not being received.
In practical terms, the blocked-list entry is intended to prevent the number from reaching you normally through calls and messages. That does not necessarily mean a caller can never leave a voicemail: the cited S21 guidance describes calls being sent to voicemail. It also does not mean that an existing text conversation is erased. The instructions describe blocking future contact, while deleting an old conversation is a separate action in your messaging app.
Treat voicemail behavior as the expected behavior described by those sources, not a guarantee for every carrier or app setup. Blocking is number-specific: a caller who uses another number, a private caller ID, or a separate messaging app may still reach you through a route the S21’s blocked-number list does not cover. A block is not a general identity-level restriction that follows someone across numbers or services.
Also popular on Amazon
- Portable and powerful USB-C HUB: BENFEI USB Type-C HUB, with super-soft and knot-free silicone woven design cable, meets most mobile office needs. Compact, lightweight, stylish, and powerful portable USB C Hub equipped with 1 x HDMI port, 1 x 100W charging, and 3 x USB ports. 18-month warranty, 24-hour response, to ensure you feel at ease when using our product.
- Design centered on comfort and reliability: Thanks to BENFEI's end-to-end in-house cable production capability, in-house PCBA and assembly capability, using the industry's most advanced silicone woven design and process, 20cm cable in length, no knots, super-soft, the HUB is easy to use in all scenarios: laptop, tablet, stand etc. Super-soft, 25000+ life cycles, to meet your daily carrying and office needs.
- 100W Charging: Support up to 90W USB C pass-through charging via Type-C port to keep your laptop powered. 10W is reserved for other interface operations. No data and video function on the Type-C port.
- 4K HDMI Display: The HDMI port supports media display at resolutions up to 4K 30Hz, keeping every incredible moment detailed and ultra vivid. Please note that the C port of the Host device needs to support video output.
- Transfer Files in Seconds: Transfer files and from your laptop at speeds up to 10 Gbps with USB A 3.2 port. Extra 2 USB A 2.0 ports are perfectly for your keyboards and mouse.
How do I unblock a number on my Samsung phone?
For a number in the Phone app’s blocked list, open Phone > More options > Settings > Block numbers, then tap the minus or remove control beside the entry. For a contact blocked from Contacts, open Contacts, select the person, tap More > Unblock contact.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsIf you blocked a conversation in Samsung Messages, check Messages > More options > Settings > Block numbers and spam to manage its blocked entries. Removing a number from one app’s list may not remove it from a separate app’s list. For example, if you added a number to the Phone list and separately blocked its conversation in Samsung Messages, review both places if you want to reverse both actions.
After removing the entry, the corresponding block is no longer in that list. If contact still appears restricted, check the app where you originally blocked it and whether another blocked entry applies. This is particularly important when you switch between Samsung and Google apps, because each app may present its own menu and blocked-number controls.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Why can a blocked number still get through?
Start by checking that you blocked the same number the caller is now using and that the call or message is arriving through the app whose block list you changed. Blocking a phone number does not automatically cover a different number, private caller ID, or a separate messaging service.
- Confirm the list: Open Samsung Phone > Settings > Block numbers and check that the intended number is present.
- Check the app: If the messages arrive in Google Messages or another messaging app, its controls may not match Samsung Messages.
- Check the caller ID: A changed, withheld, or spoofed number may not match the blocked entry.
- Check carrier options: If unwanted calls keep arriving from new numbers, look for your provider’s spam-call protection; the phone’s single-number block cannot identify every new caller.
If you cannot find Block numbers, make sure you are looking in the Samsung Phone app’s More options > Settings menu rather than the general Android Settings app. If you use Google’s Phone app, look for its corresponding blocked-number controls instead. Menu variation can reflect provider, software, or model differences, as Samsung explains in its support guidance.
If the entry is present but the contact seems to get through, compare the incoming number or message route with the entry you blocked. A different number is a different target for a number-specific block, and a messaging service outside the app’s blocked list may have its own controls. If a broader unknown-caller option is unavailable, Samsung notes that Smart Call availability varies; checking carrier spam protections is a reasonable next step, not a guarantee that every provider offers the same service.
Also popular on Amazon
- 【Read before You Buy】 Note: This adapter is USB 2.0 version and cannot transmit HDM, VGA, or other video signals. Nevertheless, they are fully capable of charging devices,duplicating files, and can be seamlessly integrated with USB-C earphones, wireless network adapters, and SD card adapters.
- 【Easy to Use and Safe】Thanks to modern manufacturing techniques, we've made these adapters sufficiently compact so that they can remain inserted in your device without noticeable protrusion or inconvenience. This means you don't have to constantly plug and unplug them, reducing the likelihood of wear and misalignment, and making them more convenient to carry around.
- 【Reliable Quality】Engineered for enhanced durability, durable aluminum alloy shell material,get excellent wear resistance and heat dissipation,the male USB C and female USB connectors & the male USB and female USB C connectors are designed to be plugged and unplugged up to 20000 times. Provides data transfer, device charging, memory space expansion, and additional computer peripherals.
- 【Think more for you】Do you need to connect a USB-C-enabled device to an odd device that only has USB-A ports? Then these USB-A male to USB-C female adapters are made for you.Simply insert the adapter into the USB-A port on the device, and you can instantly connect your USB-C device to the device that originally didn't have the correct connection port.
- 【Trusted xiwxi Quality and Service】As a responsible brand seller, you will receive xiwxi's 12-month Quality assurance and lifetime friendly customer service, you're not just buying a product,you're investing in peace of mind with all-round quality and exceptional customer service.
Frequently Asked Questions
Will a blocked caller know that I blocked them?
The Samsung and Verizon guidance describes how the phone handles calls and messages, but does not establish exactly what the caller sees or hears. Caller-side behavior can depend on voicemail and carrier handling, so do not treat a particular tone or message as proof that someone blocked you.
Does blocking a number delete its old messages?
The blocking instructions describe preventing future contact, not deleting an existing conversation. If you want old messages removed, manage the conversation separately in your messaging app.
Can I block calls but still receive texts from the same number?
The Phone app’s number-blocking guidance groups calls and messages together, while Samsung Messages also provides a separate conversation-blocking route. If you need different treatment by channel, review the controls in the specific app you use rather than assuming the Phone block is call-only.
Does Samsung’s unknown-caller setting block all spam?
No single unknown-caller control is documented as a universal spam detector. Spam identification depends on the feature and carrier available on your S21, and number-specific blocking will not identify callers who switch numbers.
Why can a blocked number still leave a voicemail?
The Samsung Galaxy S21 user manual and Verizon’s S21 support guidance describe blocked calls being sent to voicemail. The exact handling can vary by carrier and setup, so blocking should not be treated as a promise that no voicemail can be left.
Will blocking a contact remove them from my Contacts list?
No. Samsung’s Contacts procedure blocks the contact but leaves the contact in your list. You can later select the contact and choose More > Unblock contact.
Does blocking a number stop calls from every number that person uses?
No. The block is number-specific. If a caller uses a different number or private caller ID, the new route may not match the blocked entry; unknown-caller or carrier spam controls address different categories.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Why do my menus say something different from this guide?
Samsung says feature availability can vary by wireless provider, software version, and phone model. Menus also differ between Samsung and Google Phone or Messages apps, so check the app you are using and its settings.
The Bottom Line
For one known caller, block the number in Samsung Phone or block the contact in Contacts. For an unwanted text thread, use Samsung Messages and manage its blocked entries there. Use unknown-caller or carrier spam controls for broader nuisance-call categories, keeping in mind that menu availability and behavior vary. If you change your mind, remove the entry in the same app where you blocked it.
