If you turn off iMessage, your blue bubbles turn green, messages default to standard SMS/MMS (carrier-based texts), you lose features like read receipts, typing indicators, and high-quality media sharing, and syncing across your other Apple devices stops. Essentially, you switch from Apple's internet-based messaging to your carrier's basic text messaging service, which can affect message delivery and features, especially if you switch to a non-Apple phone later.
You may need to turn off iMessage if you are now using a non-Apple phone and cannot get SMS or text messages someone sends you from an iPhone.
iMessage (iPhone): A blue message bubble that stays “Sent” and doesn't update to “Delivered” for a long time suggests the iPhone is off, dead, or without internet. If it then tries to send as a green SMS and that also gets no response, it further points to the phone being offline.
The recipient isn't using an Apple phone
People using Android-based smartphones (or any other type of non-Apple phone) don't have access to iMessage. Any texts sent to non-Apple smartphones automatically appear green.
Deregister iMessage online
You should be able to receive text messages right away but it might take a few hours for some Apple devices to recognize that you're not using iMessage when they send you a message. If someone sends a message using iMessage to your Apple Account, you'll get it on your other Apple devices.
iMessages can be sent to another iPhone or another Apple device over Wi-Fi or cellular-data networks. With iMessage, you can send texts, high resolution photos and videos, documents, links, Tapbacks, text effects, Live Stickers, message effects, and more.
You may see a green bubble in the following situations: If the other person switched to an Android phone, their bubble may have turned green. There's also a chance they didn't turn off iMessage and FaceTime if they switched from iOS to Android, or maybe they changed their phone number.
Steps
If you see a green message bubble instead of a blue one, then that message was sent using RCS or MMS/SMS instead of iMessage. There are several possible reasons for this: The person that you sent the message to doesn't have an Apple device. iMessage is turned off on your device or on your recipient's device.
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.
iMessage is exclusively limited to Apple's ecosystem, restricting communication to iPhone, iPad, and Mac users only, meaning that you can't send it to Android users.
They'll still receive the messages, but they'll check them on their own time. In Messages, you'll see a small moon icon or a message saying "notifications silenced" next to their name, indicating their current status.
On your iPhone, go to Settings. Tap Messages. Set iMessage to Off.
How to send SMS instead of iMessage on iPhone
Turn your phone number on or off for your Mac
For Messages, choose Messages, select Settings, then click iMessage. For FaceTime, choose FaceTime, select Settings, then click General. Turn your phone number on or off: To turn on your phone number, select it and your Apple Account in the list.
The person with the iPhone needs to go into Settings-Messages and turn on SMS (send as SMS when iMessage unavailable)
If you're blocked it will never say delivered. It will pend blue a minute then switch to green bubble with 'Sent as Text Message' below your message. It wasn't received cuz you're blocked but that is what your phone will do.
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.
When you communicate with others who also use iMessage on an Apple device, the texts appear in blue bubbles. (SMS, MMS, and RCS messages appear in green bubbles.)
Messages automatically uses the following screen effects for specific text strings: