The simplest way to add someone on iMessage
To add someone on iMessage, open the Messages app on your iPhone, iPad, or Mac, tap the compose button (a pencil and paper icon), and type their phone number or Apple ID email address into the "To:" field. If that person has iMessage turned on and their device is registered with Apple, the field will turn blue, which means the message will send as iMessage rather than as a regular text. If it stays green, it will send as SMS instead.
That is the entire process. You do not need their permission to start messaging them, and they do not need to add you back before they can receive your message. iMessage works differently from some other messaging apps — there is no "friend request" step or waiting for acceptance.
The person will see your message appear in their Messages app the moment you send it. If they reply, your conversation will stay in the same thread. You can see whether they have read your message if read receipts are turned on (a feature you can control in your own settings).
Key Takeaways
- You add someone on iMessage by typing their phone number or Apple ID email into the compose field — no request or approval needed.
- The message will only send as iMessage (encrypted) if the recipient has iMessage enabled; otherwise it sends as a regular text message.
- iMessage conversations are tied to the phone number or email address you used, not to a separate account or username.
- Read receipts show whether someone has seen your message, but you can turn this feature off in your own settings if you prefer privacy.
- If you cannot reach someone on iMessage, they may have turned it off, switched to Android, or not registered that phone number with Apple.
Why the message turns blue or green
When you type a phone number or email into iMessage, the app checks whether that contact has iMessage registered with Apple's servers. If it does, the message field turns blue and your message will be encrypted end-to-end — meaning Apple cannot read it, and neither can anyone intercepting the data in transit. This is the security advantage of iMessage over regular SMS.
If the field stays green, it means the recipient does not have iMessage turned on, or that phone number is not registered with Apple. The message will send as a standard text message (SMS) instead, which is not encrypted by default and travels through your mobile carrier's network. The recipient will still get it, but it takes a different route and has different privacy properties.
This can be confusing because you are using the same app and the same conversation thread, but the underlying technology is different. If you are messaging someone who recently switched to Android, for example, their number might still be in your contacts, but iMessage will not find them and will fall back to SMS automatically.
Adding contacts from your phone's address book
If someone is already in your phone's Contacts app, you can start a message with them directly from the Messages app without typing their number again. Open Messages, tap the compose button, and start typing their name. Your phone will show matching contacts, and you can tap the person you want.
This is faster than typing a full number, but it only works if you have already saved that person's contact information. If you receive a message from someone new, their number will appear in the conversation thread, and you can add them to your contacts from there by tapping their name at the top of the conversation and selecting "Add to Contacts."
You can also add a contact directly in the Contacts app and then message them from Messages. The two apps are linked, so any contact you save will show up when you compose a new message.
What happens when you message someone for the first time
When you send a message to someone who does not have an existing conversation with you, it arrives as a new message in their Messages app. They will see your name (or phone number if you are not in their contacts) and your message. There is no notification to them that you have "added" them — the message itself is the first contact.
If they reply, a two-way conversation starts. From that point on, every message you send to each other appears in the same thread. You can see when they are typing (if typing indicators are on), and you can see whether they have read your message (if read receipts are on).
If the person does not want to message you back, they can delete the conversation, block your number, or straightforward not respond. Blocking someone on iMessage prevents them from sending you messages and prevents you from sending to them — the message will fail to deliver and you will see a "Not Delivered" notice.
Differences between iMessage and other messaging apps
iMessage is built into Apple devices and uses your phone number or Apple ID email as your identifier, rather than a username or handle. This means you do not have a separate iMessage account to manage — it is tied to your device and your Apple ID. You cannot create an iMessage username the way you can on WhatsApp, Telegram, or Signal.
Because iMessage is device-specific, you can only send and receive iMessage on Apple products (iPhone, iPad, Mac, Apple Watch). If you switch to Android, you lose access to iMessage entirely, and people messaging you will automatically fall back to SMS. This is one reason some people prefer cross-platform apps like WhatsApp or Signal — they work the same way on any phone.
iMessage also does not have a "contacts" or "friends" list the way some apps do. You message whoever you want, whenever you want, without building a separate social graph. This makes it simpler in some ways and less transparent in others — you cannot see a list of who has iMessage turned on, and there is no public profile to look at.
Controlling who can message you and what they see
You cannot prevent someone from sending you an iMessage, but you can control what happens after they do. If you do not want to see messages from a specific person, you can mute the conversation (so you do not get notifications), delete it, or block the person entirely. Blocking is the strongest option — it prevents them from reaching you on iMessage and also blocks their calls and SMS messages.
You can also turn off read receipts in your Messages settings so people cannot see whether you have read their message. This is a privacy choice — if you turn it off, you also cannot see whether others have read your messages. Some people turn it off to avoid the social pressure of appearing to ignore someone, while others keep it on for transparency.
If you do not want strangers to message you at all, you can adjust your settings to only receive iMessages from people in your contacts. This is found in Settings > Messages > Filter Unknown Senders. When this is on, messages from people not in your address book go into a separate "Unknown Senders" tab instead of your main inbox.
Troubleshooting when iMessage does not work
If you type someone's number and it stays green instead of turning blue, it usually means one of three things: they do not have iMessage turned on, their phone number is not registered with Apple, or they are using an Android phone. You can still message them — it will just send as SMS instead.
If a message says "Not Delivered" in red text, it means the message could not reach the recipient. This can happen if they have blocked you, if their phone is off, or if there is a network problem. Try sending again in a few minutes. If it keeps failing, ask them through another method whether they have blocked you or changed their number.
If you recently switched from Android to iPhone and your iMessage is not working, your phone number may not be registered with Apple yet. Go to Settings > Messages > Send & Receive and make sure your phone number and Apple ID email are both listed and checked. You may need to sign out and back into your Apple ID for the registration to complete.
Frequently Asked Questions
Do I need someone's permission to message them on iMessage?
No. You can send an iMessage to anyone whose phone number or Apple ID email you have. They do not need to add you first or accept a request. They will see your message appear in their Messages app, and they can choose to reply or ignore it.
What is the difference between iMessage and SMS?
iMessage is encrypted and travels through Apple's servers; SMS is not encrypted and travels through your mobile carrier. iMessage messages appear in blue, SMS in green. iMessage only works between Apple devices, while SMS works on any phone. If someone does not have iMessage, your message automatically sends as SMS instead.
Can I message someone on iMessage if they have me blocked?
No. If someone blocks you, your messages will fail to deliver and show "Not Delivered" in red. You will not be able to reach them on iMessage, and they will not receive calls or SMS from you either. The block is total across all message types.
Why did my message turn from blue to green?
This usually means the recipient turned off iMessage, switched to Android, or their phone number became unregistered with Apple. iMessage will automatically fall back to SMS when it cannot reach the person on iMessage. The message still delivers, but it is no longer encrypted.
Can I see if someone has iMessage before I message them?
Not directly. You find out when you type their number into the compose field — if it turns blue, they have iMessage. If it stays green, they do not. There is no way to check someone's iMessage status without trying to message them first.