Internet Communications Using SIP : Delivering VoIP and Multimedia Services With Session Initiation Protocol {2Nd Ed.}

The Converged Applications Environment

The converged applications environment is based on the distributed Internet
and Web architecture and is not dependent on any proprietary APIs and oper-
ating systems for internetworking of multiple servers. It is based on simple SIP
and HTTP message, flow only for all control functions. The open architecture
is especially well suited for third-party service providers across IP networks or
across the Internet. The Application Server Component Architecture for SIP
was first introduced in [3].
Figure 19.2 shows the integration of communications with applications and
transactions, as is required for e-commerce. The real-time communications
part is emphasized here with the main communication servers logically clus-
tered around the capability to exchange SIP and HTTP messages. The various
components are loosely coupled, in the sense that once their functions have
been invoked by simple call flows, the details of operation are left to each
server, without affecting the operation of other servers.

Figure 19.2 Component servers for communications, applications, and transactions

Following are the main types of communication servers:

■■ General-purpose SIP server (in the center, with database access) acting

as registrar, redirect server, and for admission control in conjunction

with the AAA and location services, such as databases or ENUM. The

redirect server also can implement private dialing plans for enterprise

networks.

Text to

Speech

Directory

& ENUM

Conference

Scheduler

Web

AAA and

Policy

Server

SIP

Srv

Service

IVR Controller

Presence

Server

UM Store

Voice Mail

Media Mixer Streaming

Content

Location

Service

Callers

Transaction

Server

IP Network

SIP and HTTP Messages

RTP Media

Gateways

SIP Clients

Gateways

Called

SIP Clients

All real time IP communication services are

implemented by SIP and HTTP call flows

Credit Card

DialingPlans Verification

SIP

Srv

Application

Service

Providers

PSTN PBX

SIP Component Services 323