Many customers would like to have a redundant network to provide uninterrupted voice services. In most cases, with an IP network in place, a second network is built for backup purposes. Figure 1 illustrates a sample customer configuration where a remote site is networked to a central site by an IP Wide Area Network (WAN). The central site has a T1 ISDN PRI facility and the remote site has two analog lines connected to the PSTN network for backup in case the IP network is not available. In these Application Notes, the configuration for redundant is from the IP Office to Avaya Communication Manager only. The Avaya IP Office – Small Office Edition handle calls at the remote site and a pair of Avaya S8710 Media Servers with a G650 Media Gateway handle calls at the central site. [Note that the name IP Office will be used to refer to the IP Office – Small Office Edition throughout this document.] The Least Cost Route feature is configured on Avaya IP Office to use the IP network as the primary route and the PSTN (analog trunk) as the secondary route to the central site.