Green bubbles mean that conversation is using SMS/MMS/RCS instead of iMessage. The contact’s current number, iMessage registration and network state matter more than your bubble-color setting. Check whether other iMessage conversations are still blue and whether the contact has a new device.
Differential
Likely causes of “iPhone messages turn green for one contact”, and how to tell them apart
- 1
The contact's number is not registered for iMessage now
What separates it The bubbles were blue and are now green for one contact, and the contact changed phone or number.
How to confirm Check whether other iMessage conversations are still blue and whether the contact has a new device.
- 2
You are sending to a number rather than to their Apple-linked address
What separates it The conversation goes to an SMS number while the contact uses iMessage through an email address.
How to confirm Start a new message to the contact's current Apple-linked address or number.
- 3
The contact has turned iMessage off or has no data
What separates it The message goes as SMS because iMessage is off or the contact has no network.
How to confirm Ask the contact to check that iMessage is on and that they have a connection.
- 4
Your own iMessage or network state is affecting it
What separates it Every conversation is green or messages fail, and iMessage shows as waiting for activation.
How to confirm Check Settings, Messages for iMessage and your connection.
Before you touch a setting
Record this first — changing settings destroys the evidence
- Whether other conversations are still blue.
- The contact's number and any recent change of phone.
- The service shown in the input field for this contact.
Try in this order
0 of 4 completedCapture the exact symptom
ReversibleCheck whether other iMessage conversations remain blue and whether the contact recently changed phone or number.
Run the smallest isolation test
ReversibleStart a new message to the contact’s current Apple-linked address/number and confirm both phones have data service.
Correct only the proven cause
ReversibleCorrect the saved destination or let the contact re-enable iMessage; avoid deleting history as a first step.
Verify before changing anything else
ReversibleSend a new test and confirm the input field identifies the intended service.
Stop boundary
When this stops being a self-service repair
- !Avoid deleting the conversation history; correct the saved destination or let the contact re-enable iMessage.
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Why did one contact's iMessage bubbles turn green?+
That conversation is now using SMS or MMS. The contact may have switched phone, turned iMessage off or be sending from another number.
Why does a contact turn green?+
Messages go as SMS instead of iMessage when iMessage is not available for that person.
Could they have switched phones?+
Yes, a change of phone can do it.