End users have no permanent IP address according to system's logic, so they must periodically register on the server to let the VoIP-core know, where the call must be routed. This can be configured on IP phone or dialer.
From the Switchboard side you must add one or few source number(s) to the end user. Routing Module transforms the called number to the "routed destination number" , then it determines the end user to which the call must be routed. You can also specify in Routing Strategies for inbound dial-peer 'did' as the most preferred method of route comparison. In case you don't, the call destinated to the end user, could be routed to provider, which provides matching country code.
Incoming calls can be billed basing on the separate pricelist.
This functionality makes possible to sell DID(Direct Inward Dial) numbers to the end users and billing such calls.
