SIP phone can use the IP Office user hot desking features, for example the default *35 and *36 short codes. However, when a different user logs in using those functions, the existing user information stored on the phone (personal directory, call log, etc) is not changed or replaced. Similarly, any local call log maintained by the phone will retain details of the hot desk users calls and other dialing. This is similar to hot desk operation on analog phones.

In addition, SIP phones continue to display the details of the user account used to originally register the phone with the system, such as typically the original user name on the display.

For IP Office Release 10.1 and higher, the support of hot desking on J129 and H175 telephones is blocked by default. This is to reflect the fact that these phones download data (call logs and personal directories) from the telephone system, rather than storing them locally, but do not replace that data when a different user hot desks onto the phone. If required, hot desking operation for those phones can be enabled using the NoUser source number SIP_ENABLE_HOT_DESK.

Hot-desking is not supported for SIP softphone applications. That includes clients running on Vantage telephones.