Do you mean the Jabber IM (chat only) client? If so, this supports Android 2.3 or later.
More info here: https://play.google.com/store/apps/details?id=com.cisco.im&hl=en
Xperia Z is shipped with Android 4.1, but you can now also get 4.2.2 for it.
If you need video calls as well, it's going to be an interesting autumn
release notes on Jabber android 9.1.3, supported devices:
Cisco supports Cisco Jabber for Android on the following Android devices:
Please remember to rate useful posts, by clicking on the stars below.