You can share the NAM 4.1 as a centralized vm, however you have to upgrade Site A to a at least Release 6.0 that’s the first release that support a NAM as centralized Vm, however the option for centralized VM was available on MICS 5.0 with a meridian switch and using the call pilot of the meridian PBX as the centralized Vm.Also you will need like mention above, MCDN code for both systems and PRI enabler on both systems. I hope that helps