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

Table 2.7 (continued)

Accessing ISDN and PSTN IN services from SIP networks [20]

SIP and QSIG for circuit-switched PBX interworking [20]

SIP for Telephones (SIP-T), for transport of telephony signaling across IP [22]

In addition to the preceding protocols interworking with ITU-style networks,

interworking with or making use of new protocols also is being investigated. See, for

example, SIP and SOAP [23].

Figure 2.4 shows an example of SIP and PSTN interworking that will be

referred to in the following and SIP-PSTN gateway service. The example also

shows a SIP-PBX gateway.

Figure 2.4 IP-PSTN gateway service and SIP-PBX gateway

SIP

Devices

PSTN and Mobile Internet

Enterprise

GWY

Phone

Fax

PSTN

Switch

PBX

PBX

Phone

Mobile

IN DNS

SIP

Server

Network

GWY

28 Chapter 2