What iOS versions does iMessage now work on?
I have iOS 9.3.5 (iPad without a SIM card), I tried to send iMessage to IOS 6.1.3 (iPhone) - writes, that it was not delivered.
[Re-Titled by Moderator]
iPad (3rd generation)
iOS 9 is ~eight years back. Pretty much everything requires a later version.
For most features: System requirements for iCloud - Apple Support
For iCloud Messages, iOS 11.4 and later, and macOS High Sierra 10.13.5 and later, and with two-factor authentication enabled.