iMessage issues

[Bobbie1974]

I have an IPhone 4. Two days ago I sent an iMessage to someone with a 4s. It was sent as a text instead although I have my settings enabled not to send as a text when iMessage is unavailable. Yesterday my iMessage was showing green in lieu of blue. I was at home where I have excellent coverage, so I'm not sure what's going on with my phone.

 

[Sirolway]

Perhaps the person you're sending to didn't have any coverage at the time?
In which case I believe the iPhone will 'drop back' to SMS ..