My iPhone can't send messages to an android

This may answer your query:

Go to Settings > Messages and turn iMessage off, then back on. Go to Settings > Messages > Send & Receive, tap your Apple ID, then tap Sign Out. Go to Settings > FaceTime, tap your Apple ID, then tap Sign Out. On your iPhone first, sign back in to iMessage and Facetime.

appleuser6363 wrote:

I can’t my iphone send messages to an android ?

The answer given above doesn't apply to your issue.

You'll need to contact your carrier. SMS is entirely a carrier function.