Contexts are logical groups of extensions. Think of contexts as sections of the Dialplan. Each section has a specific purpose and contains only extensions that are related to the purpose. One such purpose is to isolate extensions from one another. A typical example of this is "multi-tenancy". A FreeSWITCH server can service more than one business entity (tenant), and providing each tenant with its own context prevents numbering conflicts. Each tenant could, for example, have a "dial zero for the operator" extension. Users in one tenant can dial 0 to reach their front-desk extension, while users in another tenant can also dial 0 to reach a completely different extension. Another consideration for contexts is security. Phone calls that are being routed through a context have access only to the resources specifically allotted, perhaps long-distance or international dialing, or use other resources such as multi-party audio conference rooms.
There is no limit to the number of extensions...