[stevage]

Nobody I know uses iMessage.

[ghaff]

In the US, using iMessage involves flipping a switch in some Messages setting--and everyone I know in the US just texts, except for texting with international folks.

[dboreham]

Quick note that I'm in the US and my experience is: most random people use SMS; closer friends and family some use Signal, some Discord, some email; colleagues use Slack; overseas taxi drivers etc. use WhatsApp.

[pkamb]

By "use SMS" you surely mean "use iMessage" much of the time.

[spunker540]

If op is on android they wont know who uses imessage

[Auracle]

No switch flipping needed, if you send a text to another iPhone it’ll just do an iMessage instead.

[ghaff]

It may be on by default but there is a switch in Settings/Apps/Messages.