TEMA TELECOMUNICAZIONI
AD639R VoIP SIP PoE Repeater
MAS-AD639R-REV00EN
Page 24 of 30
10.4. Multicast Audio Streaming for announcements
In a LAN, the Multicast term indicates the possibility of distributing information to a group of terminals. Multicast
uses class D addresses ranging from 224.x.x.x to 239.x.x.x. In our case AD639R is able to receive audio in
Multicast and reproduce it amplified. The audio can be generated from a PC software application (for example
Adam or VLC) or directly from an IP SIP phone. The received audio in streaming is useful for reproducing voice
announcements, also called "Paging". Obviously the streaming is unidirectional, in the sense that the audio stream
is sent from the source to the destination but not vice versa. Streaming audio can be sent to several terminals at
the same time (all of which have the same Multicast address) or only to specific distinct terminals (each with its own
Multicast address). Only one audio reception address can be programmed (unlike other Tema speakers which
allow up to 16 multicast addresses), with its own playback volume. The audio supported by this mode is in the
G.711 (aLaw or µLaw), G722 or linear 16 bit high quality format (proprietary format, spread through the AD615/S
with an AD696/BM microphone base, a phone with function keys for multicast transmissions or an Intercom AA-
540).
Example 1
In a plant, there are two systems, connected to the same network switch. From a suitable phone, it is possible to
make a voice announcement via multicast address 239.255.12.42:
Both systems will play the announcement audio message. Many more devices than those given in the example can
be connected, since there are no limits.
Example 2
In the plant there are two systems with different Multicast addresses.
The phone, selecting to send the multicast voice to one or other address of the terminal, will decide which device
must broadcast the streaming message.
Extension phone
designed for
Multicast
LAN Switch
AD639R n. 1 Multicast address
239.255.12.42
AD639R n. 2 Multicast address
239.255.12.42
AD696/BM
AD615/S
AD639R
AD639R
Extension phone
with Multicast
function buttons
LAN Switch
AD639R n. 1 Multicast address
239.255.12.42
AD639R n. 2 Multicast address
239.255.12.41
AD696/BM
AD615/S
AD639R
AD639R
