Intersite Dialling Overview
BE4000 Sites in Mesh Topology
A mesh topology allows you to connect up to six BE4000 sites directly for Intersite Dialing. A mesh topology does not require a central call control platform. Selecting mesh topology leads to guided configuration where administrators can select from a list of best practice options to ensure ease of management and reliable deployment.
Note: In a mesh topology, only BE4000 sites can be connected. To connect to other call control devices, you must use star topology. For more information on star topology, see BE4000 Sites in Star Topology.
In a mesh topology, calls are routed directly from one BE4000 to the other over an IP network using SIP. Calls can be made between sites using a shorter number than dialing the whole Direct Inward Dial (DID) extension number. For example, dial 4503 rather than +1 555 123 4503. There are two dial plan options available to end users.
1.1 – Call an Extension in Another BE4000 Site Using Site Identification Number and Extension Number
Each site has 3, 4, or 5-digit extension numbers and 2-digit site identification number (also known as site ID). When calling an extension within the same site, end users dial the extension number. When calling between sites, the end users dial the site ID of the remote site and then the extension number. Key advantage of using a site ID is that you can have the extension numbers overlapping between sites and the dial plan requires less planning. Using site ID is beneficial while retrofitting Intersite Dialing to an existing deployment where the dial plan cannot natively avoid overlaps between sites.
1.2 – Call an Extension in Another BE4000 Site Using Extension Number Only
Note: BE4000 does not support calling an extension in another BE4000 site by using extension number only.
Each site can have 3, 4, or 5-digit extension number which has to be unique across all the BE4000 sites in the deployment. When dialing either within the BE4000 site or across multiple BE4000 sites, an end user simply dials the extension number. There is no need to dial the site identification number.
Key advantage of using a flat dial plan is that extension numbers are kept short (minimum 3-digit dialing) and the organization appears to be one large deployment. A flat dial plan needs up front planning. To ensure that extensions do not overlap, reserve an extension range for each site.
BE4000 Sites in Star Topology
A star topology allows you to connect any number of BE4000 sites to a centralized call control system (such as Cisco Unified SIP Proxy, Cisco Unified Communications Manager, third-party SIP provider) for site-to-site dialing. Selecting star topology leads to an advanced configuration, where administrators enter dial plan rules to route calls to the centralized call control.
There is no limit to the number of BE4000 sites that can be used in a star topology. A system can have only one BE4000 site communicating with an existing non-BE4000 call control system, or thousands of BE4000 sites connected to a Cisco Unified SIP Proxy in a retail branch scenario.
In a star topology, calls are routed directly from each BE4000 to the centralized call control over an IP network using SIP. Star topology is only recommended for administrators with a strong knowledge of SIP configuration in Intersite Dialing deployment scenarios.