The VVoIP system connects with a DISN IPVS (NPRNET or SIPRNet) but the LSC(s) is not configured to signal with a backup MFSS (or SS) in the event the primary cannot be reached.

Redundancy of equipment and associations is used in and IP network to increase the availability of a system. Multiple MFSSs in the DISN NIPRNet IPVS network and multiple SSs in the DISN SIPRNet IPVS network have been implemented in each theatre to provide network wide redundancy of their functions. They are intended to work in pairs such that one can provide its backbone services to multiple LSCs that are configured to use one as a primary and the other as a backup. This is necessary to the maintenance of backbone functionality in the event there is a circuit (network path) failure, a MFSS or SS failure, or one of the sites housing a MFSS or SS is lost or the MFSS or SS becomes unavailable. Based on this, when establishing a call on the WAN, each LSC must be configured to signal with a backup MFSS or SS in the event it cannot reach its primary.