Hi,
In Cisco Jabber release 12.1 there is a new Jabber XML key to remove/disable this message.
Make sure you have the following jabber-config.xml key set to false:
<EnablePromoteMobile>false</EnablePromoteMobile>
Unfortunately, Cisco decided to have its default value to true ☹ … and I think many customer are going to complain. So to fix this, you have to re-edit your XML files and add it ...
Regards,
Philippe