We will be implementing a new CCM 7.0 phone system at a remote site in Brazil. Exchange e-mail for all Brazilian users is housed at the main office in the United States. There is a MPLS link between sites with a 130MS response time.
Should the Unity VM server be located in Brazil or in the United States near the Exchange accounts where we can utilize an existing Unity server?
Please do not consider DR scenarios as this is more of a design question.
Best Practice is still to have Unity next to Exchange. The only calculation you need to do is figure the required bandwidth for the calls from Site A to Site B with Unity.
I usually go heavy and say:
For every 10 IP Phones with VM = 1 Unity Port or 1 call on the MPLS.
So if I have 100 IP phones with VM, that is 10 ports or 10 calls to Unity at one time over the MPLS. 10 calls * G.729 = (40K) 400k of reserved bandwidth for voice. (at least for voicemail) If they are heaving CallHandler site, factor in more bandwidth or put in a CUE at the site just for CallHandlers.