The Microsoft Planning Tool is a good start, but one of the major deficiencies in it for situations that are geographically dispersed is that wherever you enter a geographic site, it automatically assumes a new pool should go there (or at least it did when I used the tool).
The decision to deploy a new pool in a geogrphic area really boils down to 3 variables in my experience:
- number of users in geographic area
- bandwidth from the geographic area to what would be the home pool in another geographic area
- number of users and frequency of Audio/Video and Live Meeting feature usage in the area
The Microsoft OCS Planning Guide provides some guidance on this. If you are still unsure, you could always start with one Standard server, and deploy a new pool later if necessary.
Hope that helps,
Curtis
www.insideocs.com