Hi there, Dashy0405.
Is this happening with multiple contacts or a specific contact? Knowing if this is happening with only one contact or multiple can help isolate what might be going on, which can help with possible next steps.
Also, check out the information below that might be helpful, which is from this article: If you can't send or receive messages on your iPhone or iPad - Apple Support
"If you see a green message bubble
If you see a green message bubble instead of a blue one, then that message was sent using MMS/SMS instead of iMessage. There are several 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. To check if iMessage is turned on for your device, go to Settings > Messages > iMessage.
- iMessage is temporarily unavailable on your device or on your recipient’s device.
- You might need to update your settings for Messages after you set up a new device."
If none of those might be applicable, please try the steps below, which are also from the same article above:
"If you still need help
Please note, we removed some steps from that section, like ensuring that you have a good network connection, as it appears you've already done that. Those steps may help resolve this unexpected issue to not being able to send or receive iMessage.
Let us know if those help or if you've already tried those steps as well.
Take care.