If my texts are being sent as SMS on iphone out of nowhere does that mean the other persons phone is off? When usually its blue?

If my texts are being sent as SMS on iphone out of nowhere does that mean the other persons phone is off? When usually its blue?

It means that iMessage isn't available between the two of you. Yes, the other person's phone being off could do this, so could them having airplane mode on, no signal and Wi-Fi or them turning iMessage off in the settings.

Possibly.