I have an existing HP Procurve network. We recently acquired a branch off that has a 2801 and a VWIC2 T1 module. The HP routers only need a T1 card. Our PBX is at the main office and rides on its on VLAN. Do I need a PVDM card in the 2801 at this new office to carry that same voice data or will it work fine as it it?