This Expansion Module provides up to 30 additional Digital Station Ports for selected Avaya 2400, 4400, 5400, 6400, series phones and 3810 wireless phones. For systems where Direct Station Select units are being used, IP Office supports a maximum of 8 EU24’s per system, 2 XM24 Units on each Digital Station expansion module, including the IP406 Control Unit, to a maximum of 10 XM24 units per system, and two 4450 units on each Digital Station expansion module, including the IP406 control unit, to a maximum of 10 4450 units per system.