In Messages app, Why is the message text box and send icon green?

[Galaxy S6]

Using Samsung Galaxy S6. It's like when iphones send imessages, they appear as blue text box instead of a normal text box as green.

In my case, the normal text box is yellow, but for this one contact its green.

I know the contact is using a Sony Z3 so it can't be a Samsung thing. I also know that Galaxy S6's are limited with the choices of text box displays. To further add, I have no third party message apps tht would impact the display of my texts.

 

[Almeuit]

Hm that is odd. I would try deleting that thread with the person and making a new one.

 

[Timo3123]

I have the same problem. My mate said it's coming from the number that came with my phone not my ported number. One minute it's green then it's yellow? Going to give Vodafone a bell as I must be a porting issue.