We are often asked this question by customers. In fact, it may include several questions:
Our cloud system is distributed system, and we can add more units to expand whole system's capability if it is necessary. Basically, each unit can support several hundreds of concurrent calls. Of course, each unit can service several virtual servers at the same time.
Customers manage their own virtual servers. The concurrent calls of each virtual server is dynamic and it depends on online resources. That means it depends on how many local users and external lines are online. The system will make sure that all online resources can make concurrent calls. For example, if there are one online local user and one online external line, the concurrent calls of this virtual server will be 2.
Please pay attention to the key point "online". If you create several hundres of local users but only two users are onlines, the virtual server will only make sure of 2 concurrent calls.
Of course, it can be configured, but each local user is limited to no more than 3 concurrent calls. Please refer to below figure. The default value of "Max concurrent calls" is 1, that means one local user can only make one concurrent call by default.
We can configure "max concurrent calls" of each external line. At this time, it is only defined in "outgoing call" because we think peer side (for example, voip provider) will limit its own outgoing calls which is "incoming calls" of external line.
The default value is 20. Of course, it is limited by virtual server's capability firstly.