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Chapter 3
TVP-221H Telephony
Concepts
The TVP-221H enables the transmission of voice and fax traffic over any IP network by
digitizing voice and fax signals, encapsulating the information within IP packets, and then
sending the packets across the IP network
3.1 How the TVP-221H Operates
1. The TIM inside the TVP-221H digitizes analog voice signals at 8 Kbps.
2. TVP-221H system software handles the:
• Capture of telephone number presented as DTMF tones.
• Mapping the telephone number to the IP address of remote VoIP
Gateway.
• Setting up calls with remote TVP-221Hs utilizing H.323 call control
protocol.
• Digitizing, compressing and encapsulating the voice into IP packets and
transmission of the IP packets onto the Ethernet LAN.
3. A router attached to the LAN forwards the IP packets across the WAN, where
they will be received by another VoIP Gateway at the remote.
4. The process is reversed at the remote VoIP Gateway.
3.2 ATPM
To allow you to easily dial a telephone or fax on the network, the TVP-221H
maps a series of dialed digits to the IP address of the remote TVP-221H whose
phone or fax you are calling. This mapping information is contained in a database
inside each TVP-221H called the dial plan.
Based on the dial plan, the Address Translation and Parsing Manager (ATPM)
inside the TVP-221H maps telephony numbers to IP addresses of remote VoIP
Gateways. The ATPM collects telephone number dialed by users, decides whether
the dial string is part of the dial plan and, if it is, maps it to a remote TVP-221H /
TVP-224HR. When the call is set up to the destination, a sub-string of the original
dial string will be sent along to the remote VoIP Gateway.
3.3 Destination
The destination is where a call is terminated. Typically, for inbound calls from the
IP network, the TVP-221H terminals the call at one of the telephony ports. The
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