Contact name is red and it says it's not registered with iMessage

You can only send messages to other iMessage users from an iPad unless you connect the iPad to an iPhone.

How to forward SMS/MMS text messages from your iPhone to your iPad, iPod touch or Mac - Apple Support

deggie wrote:

Apparently they don't have an iPhone or they aren't using iMessage. Turn on Send as SMS in Settings.

I'm pretty sure that's not an option on an iPad. Also, all it does is make sure that, if an iMessage fails, the phone will resend it as an SMS. It has no effect at all on sending SMSs to non-iMessage users.

I think it's one of the most confusingly named options in Settings.

Not only confusing but it does not work consistently but I do think it has to be on to send to an SMS user. You are of course correct about the iPad that will only work if tied to an iPhone even if it is a cellular iPad.

deggie wrote:

Not only confusing but it does not work consistently but I do think it has to be on to send to an SMS user.

I've turned it off and sent SMS messages to test. They go through without a problem.

But, you're right that, even when it is own, messages don't always get automatically resent as an SMS when the iMessage fails.

Apparently they don't have an iPhone or they aren't using iMessage. Turn on Send as SMS in Settings.

I had to send message to myself and then in my iPhone I had to forward to the phone #