在CUCM中，Primary phone的概念出现是跟随Cisco IP Communicator(CIPC)，也就是软电话而出现的。当一个软电话的device绑定到了一个实体电话上的时候，实体电话就成为了primary phone。如果要删除处于primary phone状态的电话，必须先取消绑定关系，或者先删除绑定了的软电话设备。
Delete the Primary IP Phone
Due to these listed restrictions, when you try to delete the primary IP phone without the removal of the associated secondary soft−phone devices, you receive the Delete Failed . Cannot delete device that is used as a Primary Phone error message. Make sure to remove the association with the secondary soft−phone before you remove the primary IP phone.
Cisco Unified Communication Manager 6.x provides the ability to use adjunct licensing for a presence user who uses multiple devices. This feature allows the presence user, who already uses a Cisco Unified IP Phone, to require only a single Device License Unit instead of three when any secondary soft−phone devices are in use. The secondary soft−phone devices are limited to Cisco IP Communicator, Cisco Unified Personal Communicator, and Cisco Unified Mobile Communicator. The adjunct licensing is enabled through configuration on Cisco Unified Communication Manager, under the Primary Phone option for Cisco Unified Personal Communicator.
如果CUCM里面要新建一个Cisco IP Communicator, Cisco Unified Personal Communicator或 Cisco Unified Mobile Communicator，那么可以通过绑定已经存在的实体电话号码的方法，来达到节省License使用的目的（如果不绑定可能需要4个License，绑定了只需要1个）。