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Configuring Your System for ITSP Interoperability
About the SPA9000 Voice System and SIP
SPA9000 Voice System Administration Guide 48
3
Figure 1 SIP Requests and Responses for Internal Calls
Likewise, SIP requests and responses are exchanged to support outbound and
inbound calls that are handled through the ITSP service. In Figure 2, “SPA9000 as a
SIP Proxy for Internet Calls,” UserA and UserB are client stations that are
registered to the SPA9000. When UserA calls UserC, the SPA9000 directs the
request to the SIP proxy at the ITSP, which is then responsible for routing the
request to UserC. After the session is established, RTP is anchored by the
SPA9000.
Figure 2 SPA9000 as a SIP Proxy for Internet Calls
SIP UA
SIP UA
SIP Proxy
SIP Proxy
RTP
1
2
3
4
SIP Proxy
SIP Proxy with
media proxy enabled
Internet
IP Router (firewall)
Broadband modem
Hub/switch
SPA9000
UserA
UserB
UserC
Internet (WAN)
Interface
ITSP
ISP