I have never used the messages app on my late 2009 iMac, and I just realized it would be nice if I could see the messages on my iPhone 15. I don't know how to set up the iMac messages to send and receive text messages
[Re-Titled by Moderator]
Original Title: iMac using High Sierra not linked to my iMac
Macs are not cell phones, and so cannot participate directly in the SMS, MMS, and RCS messaging systems. But with the aid of an iPhone, a Mac can send and receive such messages.
What is the difference between iMessage, RCS, and SMS/MMS? - Apple Support
Forward text messages from your iPhone to other devices - Apple Support
Provided that you're running the latest release of High Sierra, it appears that your Mac would meet the minimum requirements for using either Text Message Forwarding (Yosemite), or Messages in iCloud (High Sierra 10.13.5). Apple could raise the minimum requirements in the future, but for now you should be OK.
Continuity features and requirements for Apple devices - Apple Support
System requirements for iCloud - Apple Support
Also see:
Messages for iPhone, iPad, Apple Watch, and Mac - Official Apple Support
How do I set up Messages on iMac with macOS High Sierra to sync with iPhone?
