Installation guide

334 Planning and Installation Guide ShoreTel 14.2
Legacy Integration PSTN Services
18
PSTN Services
The number of trunks, your integration plan, and the overall system design includes the provisioning of
services across the network. PSTN services can be provided at both systems in the integration or
consolidated together on one system.
Multi-Site Integration
When the systems are located at different sites, both systems should have local trunking for both
inbound and outbound calls. Local inbound numbers make it easy for nearby customers to reach you,
while local outbound trunks allow you to save on telephone charges by using local services at the site.
In this configuration, the trunk lines connecting the systems are used for the inter-site calling between
extensions or applications on the two systems. The interfaces on the two systems are configured to
dial out to the remote or off-system extensions, and to accept incoming calls using DNIS.
The ShoreTel voice switch that connects to the legacy PBX should be located at the site with the
legacy PBX. This leverages the IP network to extend the calls to the other sites with the ShoreTel
system.
Single Site Integration
When the systems are located at the same site, it is not required that both systems be connected to
the PSTN. The systems can be configured to best match your requirements.
In a single site configuration, the PSTN connections for inbound calls can be connected to each
system. In this environment, the trunks connecting the two systems are configured to dial out the
remote or off-system extensions and to accept incoming calls using DNIS.
Alternatively, inbound services can be consolidated on either the ShoreTel system or the legacy PBX.
In this environment, calls to users on the other systems are forwarded to the remote or off-system
extensions through the trunk lines connecting the systems.
When all inbound trunks are consolidated on the ShoreTel system, the trunks are configured to support
off-system extensions within the range of extensions on the other PBX.
When all inbound trunks are configured on the legacy PBX, the trunks on the ShoreTel system are
configured to support inbound services with call routing to the extensions on the ShoreTel system.
When DID numbers are already in place on one of the PBX’s which will be connected, ShoreTel
recommends that the inbound DID service not be moved or split between the systems but configured
to remain on the system where they are currently configured and have calls to users on the other
system forward across the connecting trunks.