Determining how many users will be using the BlackBerry MVS at one time
When you consider how many users will be using the BlackBerry Mobile Voice System at one time, a reasonable assumption is that 10% of BlackBerry MVS users will be on a call at any given time, and half of those users will be using their BlackBerry MVS Client instances. If your call patterns vary drastically, you will have to adjust the calculations.
In an environment with 100 BlackBerry MVS users, you can expect to have ten users on a call at a time. Of those ten users, five will be using their BlackBerry MVS Client instances. For these ten calls, 20 channels are in use - one ingress and one egress on the network between the PBX and the BlackBerry MVS. For the five calls to the BlackBerry MVS Client instances, five channels are used on your PSTN trunks.