Flex-ICX is a software application that provides call-routing services in an IP telephony network. Using Flex-ICX, service providers and enterprises can create large-scale, highly reliable packet voice networks.

Flex-ICX is part of the FlexSERV Voice Infrastructure and Applications (VIA) solution for service providers. Service providers can use the Flex-ICX Server to offer voice services between SIP-based application service providers (ASPs) and the public switched telephone network (PSTN). The Flex-ICX Server also provides residential voice services over broadband access as part of the Flexsolv Broadband Local Integrated Services Solution (BLISS). Enterprises can use Flex-ICX  for internal IP telephony transit among enterprise voice gateways and SIP-capable IP PBXs, as well as interconnection with the PSTN.

Flex-ICX accepts registration requests from SIP endpoints such as IP telephones, residential voice gateways, and PC applications, creating a dynamic record of the endpoint’s current contact address. Static registrations can also be configured directly on desired endpoint. If no match is found in its registry, Flex-ICX can use external Telephone Number Mapping (ENUM) or location request (LRQ) queries, or locally configured static routes to determine where to forward the request.

Flex-ICX can perform a digest authentication of SIP Register and Invite requests, and can encrypt SIP requests and responses using Transport Layer Security (TLS). Flex-ICX can generate RADIUS accounting records for all call attempts.

Redundant deployment of Flex-ICX can provide high availability and increased performance. Both  in a pair are active, sharing dynamic registration data. An external means, such as Domain Name System (DNS) services (SRV) records, must be used to distribute SIP requests between in a redundant deployment.

A Graphical User Interface (GUI) is provided to configure Flex-ICX . Configuration data is stored in a local database, which is automatically replicated in redundant deployments. A Simple Network Management Protocol (SNMP) interface is also provided to monitor and control Flex-ICX .