Carrier-grade Signalware® SIP provides a complete development and deployment environment for customer-developed applications based on the SIP signaling protocols. This includes the combination of flexible SIP protocol access and platform management features that simplify the development process. Signalware SIP is a robust solution that is built on the same proven fault-resilient platform as Signalware SS7 and SIGTRAN.
Signalware SIP's high availability and scalability distinguish it from other SIP offerings. Features such as multiple computer element clusters and application failover and restart ensure revenue will not be lost due to downtime. Signalware SIP APIs can be added along side of SS7 or SIGTRAN signaling nodes to take advantage of Signalware's proven operational environment. Signalware SIP can also be deployed in a standalone environment, reducing product life cycle costs since one signaling platform supports multiple customer products.
The SIP architecture is modular and provides a simple, easy to use development environment for handling SIP session control. Signalware SIP allows developers to maintain state information at either the transaction level or at the call level. Because it is modularized, the underlying transport protocol (UDP, TCP, SCTP) is transparent from the user application. This transparency hides the communication details so developers can concentrate on the application.
Signalware applications can access the SIP protocol stack using any of the three abstraction levels as shown below: Protocol Function, Transaction Function, and Call Function. In addition, Signalware SIP includes important Routing and Management Functions that support the high availability features of the product.
Protocol Function
The Protocol Function provides low level encoding and decoding of SIP message formats. This is the lowest level that the developer can use to access SIP communications services. Signalware SIP is compliant with the latest IETF standards (RFC 3261, RFC 2327). The SIP library performs SIP parsing of standard requests (INVITE, ACK, BYE, CANCEL, REGISTER, OPTIONS) and responses. Optional SIP extensions (INFO, PRACK, SUBSCRIBE, NOTIFY, UPDATE, REFER, MESSAGE) support 3G wireless requirements for presence, availability and instant messaging services. The protocol function does not reject unrecognized extensions. Any unrecognized data is passed on as raw data to the application for further deciphering. This allows the developer to handle many proprietary extensions or special encoding defined by a SIP extension.
Routing Function
The SIP router uses the underlying reliable and unreliable transport services (TCP, SCTP, and UDP) over IPv4 or IPv6. TCP and UDP are provided by the commercial operating system (OS). SCTP protocol is provided either by Ulticom or the commercial OS as a selectable option. Once an application registers for Signalware SIP services, the router listens for incoming messages on the designated port number(s) and sends SIP messages to the application based on the combination of Call-Ids and port number. The SIP router sends outbound messages based on the following criteria:
Management Functions
SIP management functions include SIP stack management, virtual IP management, and events and measurements. The SIP stack manager handles initialization and registering applications with the SIP stack. The virtual IP manager is a distributed function that monitors the IP connections to the network and initiates IP-takeover in the event of a failure of a connection within the Signalware cluster. Signalware SIP collects and stores measurement information, handles event logging via standard Signalware methods, provides debug tracing and monitoring capabilities, and handles MML commands for the SIP stack management. Ulticom's Signalware SIP product is easy to use and provides low-level access to SIP messages.