Yealink SIP-T28P - Manual (Page 131)

Advanced Phone Features
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3. Click Confirm to accept the change.
Note
To send RTP stream:
1. Press the multicast paging key when the phone is idle.
The phone sends RTP to a preconfigured multicast address (IP: Port). Any phone in
the local network then listens to the RTP on the preconfigured multicast address (IP:
Port). For both sending and receiving of the multicast RTP, there is no SIP signaling
involved.
The multicast paging key LED illuminates solid green.
The following figure shows a multicast RTP session on the phone:
2. Press the Hold soft key to place the current multicast RTP session on hold.
3. Press the Cancel soft key to cancel the multicast RTP session.
Note
You can configure the phone to receive a Real Time Transport Protocol (RTP) stream from
the pre-configured multicast address(es) without involving SIP signaling. You can
specify up to 10 multicast addresses that the phone listens to on the network.
How the phone handles incoming multicast paging calls depends on Paging Barge and
Paging Priority Active parameters configured via web user interface.
Paging Barge
Paging barge parameter defines the priority of the voice call in progress. If the priority
of an incoming multicast paging call is lower than that of the active call, it will be
ignored automatically. If Disabled is selected from the pull-down list of Paging Barge,
If G722 codec is used for multicast paging, the LCD screen displays the icon to
indicate that is providing high definition voice.
Default codec for multicast paging is configurable via web user interface only.
Multicast RTP is one way only from sender to the multicast address(es) (receiver). For
outgoing RTP multicasts, all other existing calls on the phone will be placed on hold.