If it doesn't work on your Mac It's most likely because you're on Mac OS X 10.3 or 10.4 - If you need a version for Mac OS X 10.3 or 10.4 let me know and I will Build it for Mac OS X 10.3 and 10.4. CNET Download provides free downloads for Windows, Mac, iOS and Android devices across all categories of software and apps, including security, utilities, games, video and browsers.
You don't need to download anything.
Ichat For Mac
iChat does not sync with your iPhone.
Messages 7.x.x and Messages 8 do (in Mountain Lion and Mavericks).
The Mac version of Messages can still send SMS messages to US registered phone on these carriers.
This will mean setting up an AIM or AIM valid Screen Name in Messages.
You then add the telephone number with a leading +1 to the Buddy list.
i.e. the buddy's name becomes '+1234567890'
Apple Ichat Download For Mac
This is not a real number but you can add it to a Buddy list and you will get a text error message back from the AIM servers
Said 'Buddy' in a Buddy List
Alternatively they can use an AIM capable app you your can Message each other that way.
Same with a Jabber app and names from Facebook and GoogleMail (Messages allows you to join Jabber servers as well)
Download Ichat For Windows
You can also join the Yahoo service in Messages so your Windows Buddy could use a Yahoo able app.
They could of course login to many of these services via a web browser and chat there.
Ichat Download 10.4
9:37 pm Friday; March 7, 2014
iMac 2.5Ghz i5 2011 (Mavericks 10.9) G4/1GhzDual MDD (Leopard 10.5.8) MacBookPro 2Gb (Snow Leopard 10.6.8) Mac OS X (10.6.8), Couple of iPhones and an iPad