If you are not receiving verification codes, the cause is usually one of three things. Your phone filters the text into an unknown-sender or spam folder, or misses it because of a full inbox or no signal. The sender's risk checks stop the code before it is sent. Or the sender refuses your number type, such as a VoIP number. Check the phone first, then the account, then the number.
Which cause matches your symptom?
The pattern tells you where to look. When every service fails, the cause is usually on your phone. When one service fails, the cause is usually on that service's side.
| Symptom | Most likely cause | First thing to try |
|---|---|---|
| No codes from any service | Phone-side filter, full inbox, no cellular signal, or a setting that blocks short codes | Check unknown-sender and spam folders, clear old messages, toggle airplane mode |
| No code from one service | Too many requests, a risk check, the wrong number on the account, or a refused number type | Stop requesting, confirm the number on file, try another verification method |
| Codes arrive late | Weak signal or roaming on your side, or limited SMS service in your region on the sender's side | Move to better signal and wait for the pending code instead of requesting a new one |
| Code arrives but is rejected | An older code from an earlier request, or a typo | Use only the newest code you received |
For how text codes work from the sender to your phone, see how a text verification code works. If the missing code is from Telegram, the code may be going to the app instead of your texts, which has its own fix.
Is your phone hiding the code?
Phone-side filters are a frequent cause and the quickest to fix. Check these before you request another code.
iPhone: Unknown Senders filtering
Apple's guidance is direct: "If you use the Unknown Senders filtering in the Messages app, check there for your verification code" (Apple Support). Codes come from numbers you have never saved, so the filter catches them. To get alerts for those messages, Apple says: "Go to Settings and tap Apps. Tap Messages, then scroll to the Unknown Senders section and tap Allow Notifications."
Android: Google Messages spam protection
Google Messages can hold texts before you see them. Per Google's help page, "When Google Messages detects suspected spam, it can prevent spam messages from getting delivered and hide spam in the spam folder." The toggle is in Messages settings, under Protection & Safety, Enable spam protection. If you once reported a code sender as spam, Google says that blocks the sender and moves the conversation to Spam & blocked. Open that folder and unblock the sender.
Inbox, signal and the number on file
Full inbox or a broken messaging app. Microsoft lists this cause too: "If your phone's message inbox is full or if you're using a messaging app that's malfunctioning, the verification SMS might fail to appear" (Microsoft Support). Delete old threads. If you use a third-party SMS app, switch back to the default app for one attempt.
Signal and airplane mode. SMS travels over the cellular network. A phone can show full Wi-Fi and still have no usable cell signal. Toggle airplane mode on and off so the phone reconnects to the network, then wait for the pending code.
Short codes and blocked numbers. Many services send codes from short codes rather than full numbers. Some phone plans and account settings can block messages from short codes. If no service can reach you, ask your carrier to check your line. Also check your phone's blocked-numbers list for the sender.
The wrong number or country code. A code sent to a mistyped number, or to the right digits with the wrong country prefix, goes to someone else. Open the account's security settings and read the number on file digit by digit, country code included.
Is the service refusing to send the code?
Senders run their own checks before they spend money on an SMS. When a check fails, nothing reaches your phone, however good your settings are.
Too many requests
Pressing "resend" repeatedly makes things worse. Microsoft warns: "Don't make excessive or repetitive requests to alternative emails or phone numbers as this can cause us to block you and not send verification codes." If a code still has not arrived after a couple of requests, stop requesting and work through the phone-side checks.
Risk checks
Microsoft also says: "If your actions trigger alerts or deviate significantly from your typical patterns, we might interpret it as potentially risky behavior, leading to temporary block where we won't send codes." A sign-in from a new country, a new device, or a VPN can look different from your usual pattern. When you are on a VPN or proxy, the sender sees that connection's location, not yours. Check what it shows before you request again:
What does your IP reveal right now?
Regional limits and prompts
Regional SMS limits. Some regions have limited SMS service. Per Microsoft: "If you're in a region where Microsoft's SMS services have limited functionality or are temporarily unavailable, this could prevent the code from being delivered." If the sign-in screen offers an app, email or voice-call option, use it.
A prompt instead of a text. Google's 2-Step Verification help notes that Google may send a prompt to your signed-in phone instead of a text. Check your phone for the prompt. The same page says delivery depends on your plan, device, location and carrier. If you requested several codes, only the newest one works, which explains many "code rejected" errors.
Does the service accept your type of number?
Number type decides whether some senders will text you at all. Microsoft states: "VOIP numbers cannot be added as a way to sign in or get verification codes. Please add a mobile phone number." Google says of its own Voice service: "Some websites, such as banks or subscription services, won't send text messages to Google Voice numbers" (Google Voice Help).
Virtual and app-based numbers fail in two ways. Some services refuse the number when you enter it, which is covered in this phone number cannot be used for verification. Others accept the number and then never send to it. For how senders tell the two types apart, read why VoIP numbers fail SMS verification.
Where does a non-VoIP number fit?
A non-VoIP number only helps if the cause is your number type. VoidMob (mobile proxies on real 4G/5G devices, non-VoIP SMS verification and eSIM) sells only non-VoIP carrier numbers, never VoIP.
A one-time verification number is a US number, active for 15 minutes, and can receive several codes in that window. If no SMS arrives, the rental cancels and refunds in full automatically. The exception is services marked non-refundable, which end without a refund. Once a code has been delivered, the rental cannot be refunded. Poll for the code instead of cancelling early: frequent cancellations pause SMS purchases for 24 hours. If you need the number for longer, rentals run 3, 7, 14 or 30 days, and a dedicated monthly line is offered per country.
Why is my phone suddenly not getting verification codes?
A sudden stop usually means a new filter or block on the phone (Unknown Senders on iPhone, spam protection or a blocked sender in Google Messages), a full inbox, or a sender that has paused codes after repeated requests or an unusual sign-in. If every service fails at once, ask your carrier to check whether your line blocks short codes.
Why isn't my verification code sending to my iPhone?
Check the Unknown Senders filter in Messages first: Apple says verification codes can land there. To get alerts for those texts, go to Settings, tap Apps, tap Messages, scroll to Unknown Senders and tap Allow Notifications.
Where is SMS located in Settings?
On iPhone, go to Settings, tap Apps, then tap Messages. On Android with Google Messages, the settings are inside the Messages app, where Protection & Safety holds the spam protection toggle.
How do I enable SMS verification codes?
Add a mobile number as a sign-in or verification method in the account's security settings. Microsoft only accepts mobile numbers here and refuses VoIP numbers for sign-in or verification codes.
Why am I not receiving the 6 digit verification code?
The causes are the same for any code length: a phone-side filter, a sender risk check or a refused number type. If a code arrives but is rejected, you probably requested more than one. Google's help says only the newest code works.
Receive codes on non-VoIP carrier numbers
One-time numbers active for 15 minutes, refunded automatically if no SMS arrives (except services marked non-refundable), plus multi-day rentals and dedicated monthly lines.