Multi-Facility Inbound Redundancy and Shared Telephony

Configure your PBX properly to ensure support for multi-facility inbound redundancy.

When multiple facilities share a PBX, you must specify separate Guest and Direct Access numbers for each facility to realize speech recognition benefits for incoming callers.

Important: To take advantage of multiple facility inbound redundancy features using shared telephony, your PBX must be configured properly and you must have a uniform dialing plan for the facilities.

For example, let's consider this scenario when a deployment has three facilities: West Philadelphia, South Philadelphia, and Center City (the principal facility). The following table shows the grammars searched for speech recognition at the hunt group prompt when each facility has a separate hunt number and all facilities share a pool of lines for incoming calls. The system relies on the DNIS to determine which facility's grammars to use for the incoming call.

The following table shows information on shared telephony with one shared pool of lines for all facilities.


Guest and Direct Access Numbers

Grammars Searched

West Philadelphia



  • West Philadelphia

  • Global

South Philadelphia



  • South Philadelphia

  • Global

Center City



  • Center City

  • Global

The following figure illustrates inbound redundancy is achieved using shared telephony between multiple facilities.

  1. Someone places a call to a Vocera device user.

  2. The Central Office routes the call.

  3. The PBX skips the VSTG that is down (even though it is in the routing table).

  4. The call is routed to the VSTG that is online.

  5. The call is received by the Voice Service, which knows which facility's grammars to use based on the dialed number.

  6. The Vocera device user receives the call.