I'm planning to use the FMS/FMG platform to provide internet based VoIP access to my PBX.
In order to estimate the cost of such a deployment, I would like to know how many call can be handled by a single FMG as it seems that the FMG is the bottleneck (performing the media conversion).
Conservatively, we certify FMG/FMS for only 150 concurrent calls on a typical setup. There isn't a hard limit closeby 150 calls in programming of FMG (except in licensing terms). In specific situations, actual usage may stretch to multiples before other servers in network chain or FMG show sign of stress. However, stressing beyond recommended capacity is best avoided.