The IP406 supports 6 Expansion Modules providing a combination of up to 190 analog and digital extensions, with capacity for 8 analog trunks or 3 digital trunks (72 T1/PRI channels and 90 E1 channels).
The IP412 supports 12 Expansion Modules providing a combination of up to 360 analog and digital extensions, with capacity for 8 analog trunks or 4 digital trunk (96 T1/PRI channels or 120 E1 channels).