We are currently using a kind of phone SSO during windows user logon and we are using Jabber to control the desk phone (use my desk phone for calls). All our phone and computers are tethered (computer connected to phone)
If user has more than one phone to control, Jabber automatically select the latest used one which may not be the correct one.
The idea is to have a kind of API to be able to change the phone association in jabber so users don't need to change it (or at least check) each time they logon on (CUPC had this feature called AutomaticTetheredPhoneSelection).
PS: Currently in 11.8.4 we change parameter device_service-phone.deskphone.device in jabberlocalconfig.xml but this method is no more possible in latest jabber versions because of configuration files being encrypted ....