I cannot send messages to an android phone

Your carrier is giving you bad information. SMS is a carrier function. You need to call them back and escalate the issue. And yes, I know that they don't want to do that. They want to get you off the phone as quickly as possible because they all have quotas for the number of calls they have to answer every hour.

Note that it is not possible to turn off directly on the phone. The "Send as SMS" feature only affects iMessages that have failed to send as iMessages. It has absolutely nothing to do with sending SMS messages to Android users. So, while I recommend leaving it on generally, it doesn't matter which way you set it in this instance.

Make sure it's txt messages and not iMessages, even if it should be automatic

Did you toggle on 'send as SMS' in Settings>Messages?

Cdlanglois wrote:

Thank you! I will try that

I wish you the best of luck!

I'm really glad to hear that!