Description This book explains why people and companies are using SIP equipment and software to efficiently upgrade existing communication systems to develop advanced communications services and to more easily integrate these systems with other information systems and services. SIP is uses well-established communication protocols that has many low cost devices and software application development tools available. The use of SIP products and software allows companies to cost-effectively upgrade and eventually replace existing (legacy) communication systems with more cost effective and easy to use IP based equipment. Because SIP uses standardized Internet protocols, this allows end-users and system administrators to have more control and even develop communication services (such as video mail) that have been traditionally been unchangeable and limited. SIP is a text-based protocol (similar to web HTML) which allows for relatively easy development and integration with existing company information systems to produce new revenue producing services (such as integrating mobile telephone and order processing systems). Although SIP is an industry standard, not all SIP systems and services are the same. There are cost and quality tradeoffs along with common problem areas and risks. There are many ways SIP systems can reduce communication costs along with the ability to create new revenue producing services. This book will help you to understand what SIP is, how it operates, what services it can provide and how companies can benefit from implementing systems that use SIM. Some of the most important topics featured are: • Function parts of SIP systems Sample Diagrams There are 32 explanatory diagrams in this book SIP system This figure shows the basic functions of the SIP system. This diagram shows that a user equipment device (a mobile phone in this example) is calling another device (a landline telephone). The UE sends its connection request (an invite) to the proxy call session control function (P-CSCF). The P-CSCF needs to find the call server so it sends a request to the interrogatory call session control sever (I-CSCF). The I-CSCF contacts the home subscriber server (HSS) which contains the service profile of user and the location of the serving call session control function (S-CSCF). The S-CSCF will then manage the communication session with the UE through the P-CSCF. The SIP system can then connect a call through a media gateway (signaling processes not shown) so the connection can reach the landline telephone. 
SIP Billing This figure shows how SIP billing system can use a combination of offline charging and online charging processes. For offline charging (post billing), charging event information (network function usage information) is accumulated and assigned to accounts in the charging data function (CDF). The CDF produces CDRs that are provide to the charging gateway function (CGF) which adapts and sends call session usage records to the billing system. For online charging, some network elements (such as the S-CSCF or MRFC) request service authorization before providing access to services. The online charging system interfaces directly with the billing system to reserve and post charges directly to the users billing account. 
About the Author Mr. Lawrence Harte is a communications expert with over 29 years technical and business experience. As of 2008, he has authored over 100 books and is an inventor of several communication patents. His many degrees and certificates include an Executive MBA from Wake Forest University and a BSET from the University of the State of New York. |
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