The Avaya IP Office IP406 V2 Office is the new 406 hardware. The IP Office IP406 V2 Office base unit is 19" rack mountable. Optional internal upgrades allow for the support of up 12 x V.90 modem calls and a 5, 10, 20 or 30-channel Voice Compression Module (VCM). The VCM module supports 4, 8, 16 or 24 simultaneous Voice over IP sessions. These can be used for either providing networking between sites over a Wide Area Network or supporting IP Telephones and Soft phones. An IP extension only uses the compression module whilst on a call to a non-IP extension/line.