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Administrator Guide for Cisco Unified MeetingPlace H.323/SIP IP Gateway Software Release 5.2.1
OL-6571-02
Chapter 1 Introducing Cisco Unified MeetingPlace H.323/SIP IP Gateway Software Release 5.2.1
Information About Cisco Unified MeetingPlace H.323/SIP IP Gateway Software Release 5.2.1 Components
How PSTN and Cisco IP Phones Communicate by Using Cisco Unified MeetingPlace H.323/SIP IP
Gateway Software Release 5.2.1
When a call is placed from a PSTN phone to a Cisco IP phone, the call is routed through a voice gateway,
which is the demarcation point where the circuit-switched voice network meets the packet-switched data
network. The primary responsibility of the voice gateway is to ensure that PSTN voice traffic reaches
the data network and vice versa. You can use the voice gateway to forward an IP or PSTN call to its
opposing network through Cisco Unified CallManager or a PBX.
When a call is placed from an Cisco IP phone, it is routed to Cisco Unified CallManager, which is
responsible for setting up the call, directing the call to the called device, and sending network
information— such as the IP address, UDP port number, and communication capabilities of the called
device—to the Cisco IP phone. After receiving the information, the Cisco IP phone sends its digitized
voice traffic directly to the called device.
The following steps describe how Cisco IP phones and PSTN phones use Release 5.2.1 to access the
Cisco Unified MeetingPlace Audio Server system, as shown in
Figure 1-1
.
Figure 1-1
Cisco IP Phones and PSTN Phones Using Cisco Unified MeetingPlace H.323/SIP IP
Gateway Software to Access the Cisco Unified MeetingPlace Audio Server System
.
Step
Cisco IP Phone Description
PSTN Phone Description
1.
On the Cisco IP phone dial pad, the caller enters a
dialable number to the Cisco Unified
MeetingPlace Audio Server system that will host
the meeting.
By using a PSTN phone, the caller dials the number
to the voice gateway.
2.
The call is immediately routed by using SSP to
Cisco Unified CallManager.
The voice gateway routes the call to Cisco Unified
CallManager.
Cisco IP phone
Cisco CallManager
PSTN phone
Cisco
MeetingPlace
Audio Server
Cisco MeetingPlace
H.323/SIP IP Gateway
Voice gateway
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