A primary appliance, reversibly engageable with a secondary appliance for sharing credentials, including: a credentials module configured to enable the primary appliance to make/receive phone calls; and an interface with the secondary appliance, the interface including: a physical interface for physically reversibly engaging the primary appliance and the secondary appliance; and a conductive interface for enabling the secondary appliance to communicate with the module upon being physically engaged. A secondary appliance, reversibly engageable with a primary appliance having a credentials module enabling the primary appliance to make/receive phone calls, including: a service module configured to be enabled by the credentials module; and an interface, for the primary appliance, including: an interface for physically reversibly engaging the secondary appliance with the primary appliance; and a conductive interface for enabling communication of the secondary appliance with the credentials module upon the secondary appliance being physically engaged with the primary appliance.