"User busy" can mean blocked, but more often means the person is on another call, has their phone off, is out of range, or has a "Do Not Disturb/Focus" mode enabled, especially if it's just occasional; a consistent, immediate busy tone without ringing might signal a block, but you can't be certain without someone else calling them. A quick ring followed by a busy tone is a stronger sign of being blocked, while no ring at all usually means DND or phone off.
A busy signal or fast busy signal followed by a dropped call might mean your number is blocked through their carrier. If you experience this over several days, it points to being blocked.
Signs someone has blocked your number
Busy Schedule
The person may be busy with other tasks like meetings, travelling, and doesn't want to be interrupted. In such situations, they might choose to decline the call and talk to you later.
The most common reasons are the flight mode, call barring, call forwarding or call auto-reject.
A blocked number may ring only once and then go to voicemail. (NOTE: It's also possible that the person is on another call, has their phone turned off, has a low battery, or has it set to airplane mode.) Mask your number (by dialing *67 first) or you call from someone else's phone.
How to reject calls silently so it looks like I'm busy? On Android, set the contact's ringtone to “None” and enable “Direct to voicemail”.
You can suspect someone blocked you on an iPhone if calls go straight to voicemail (maybe after one ring) and iMessages don't show "Delivered" or "Read" receipts, but these signs can also mean their phone is off; the most reliable test is trying to call them using a different number or *67 to hide your caller ID, and if it rings normally on their end but goes to voicemail from your real number, you're likely blocked.
The person who has blocked you will never see messages or calls from you. If a person unblocks you, messages are not resent. They will never see information that you sent while they had you blocked.
Undelivered texts could be a sign that the person you're trying to reach doesn't have service … or took steps to avoid communication by blocking your number. “Blocked calls are different from declined calls because your phone call never gets to the person you're trying to reach.
To know if someone blocked you, watch for calls going straight to voicemail after one ring, texts showing "Not Delivered" (or no read receipts/checkmarks on apps like WhatsApp), and potential changes on social media; the most definitive test is calling from another number, where it rings normally for you but goes to voicemail on your original number, indicating a block.
When you text someone who blocked you, the message generally sends from your end but is blocked from reaching the recipient; you typically won't get an error message, but you won't see a "Delivered" notification (on iPhones, it might stay blue but lack delivery confirmation, while on Android, it might show "Not Delivered" or just hang, but you can't know for sure without them telling you or trying other methods like calls to voicemail or different apps).
The person you blocked will not realize you blocked them when they try to call you. On their end, they'll hear the phone ring a few times. Then, their call will go straight to voicemail.
You can tell if someone blocked your number if your calls go straight to voicemail (after one ring), texts show as undelivered (like on WhatsApp), or you're blocked on social media; however, the surest way is to call from another phone: if your calls don't go through from your number but do from another, you're likely blocked, though consistent patterns over time are key to differentiate from normal DND/airplane mode.
Your text messages don't deliver
If your text messages aren't going through, it could mean the intended recipient has blocked your number. Most devices and messaging platforms indicate undelivered messages with a “Not Delivered” status message or a symbol, like a red exclamation point.
The line is currently in use: The individual you are trying to reach is on another call, and their network does not support call waiting or does not forward additional calls to voicemail. You may be blocked: Some carriers or phone configurations show "User busy" or a similar message if your number is restricted.
Calls go to voicemail after one ring
One of the quickest ways to know if someone has blocked your number is to call them. If your call goes to voicemail after one ring, this could be a sign that your number has been blocked.
The answer is yes and no. If you call a phone number and hear a busy signal after a while, this does not mean that the recipient's blocked your number. This means that the person you are trying to reach is engaged on another call, or has set their phone to divert incoming calls to voicemail.
Muting helps you ignore someone without preventing them from doing anything. Blocking someone prevents them from messaging you, commenting on your observations, identifying your observations, and otherwise interacting with you on iNaturalist.
SMS is a cellular carrier technology where Apple controls iMessage. If a person blocks you on iMessage, then they won't get any of your texts at all.
Reasons for a busy signal
The called number is talking with another caller on the phone. The number is calling out. Someone else has called the number or is calling the number at the same time. The other line was left off-hook.
Call using another phone number or a hidden number
The person's phone is probably switched off or in airplane mode or “Do Not Disturb” mode. However, if it rings just once (or a half-ring or abbreviated ring) and goes directly to voicemail, then it's very likely your number has been blocked.
Do Not Disturb mode (DND) is your go-to solution for stopping incoming calls without having to block anyone.