The 536M expansion module is designed to increase the power and flexibility of the 5i Series VoIP phones. Up to three modules can be used with the 55i or 57i telephone to create a powerful, feature rich VoIP phone console. The 536M console module shares power and signaling with the phone, eliminating the need for additional wiring. Designed for receptionists, administrative assistants, call center agents, power users, and executives who need to monitor and manage a large volume of calls on a regular basis, the 5i Series Expansion Modules provide an intelligent choice for all Enterprise IP environments.