Aastra Telecom 9480i CT Series User Manual

Page of 1184
Operational Features
5-108
41-001160-03, Rev 00, Releaes 2.4  
IP Phone Administrator Guide
How it works
After pressing a configured “Paging” key on the phone, the Phone sends RTP to a 
preconfigured multicast address(es) (IP port). Any phone in the local network 
then listens for RTP on the preconfigured multicast address(es) (IP port). For both 
sending and receiving of the multicast RTP there is no sip signaling involved. The 
Phone displays the multicast RTP sent/received address(es) to the user.
The phone uses a preconfigured G711 uLaw CODEC for multicast RTP. 
For Paging Systems, the phone only plays RTP traffic; users have the ability to 
drop a rogue page. The recipient can drop the incoming page if required. The 
recipient can also set Do Not Disturb (DND) to ignore any incoming pages.
For incoming RTP multicasts, the ringing display is dependant on the “Allow 
Barge-In
” parameter. If this parameter is disabled
and there is not other call 
on the phone, then the paging is automatically played via the preferred 
audio device (see the model-specific IP Phone User Guide for setting 
Audio Mode on the phone).
If there is an existing call on the phone, 
the call initially displays in the ringing 
state. The user has the option to accept/ignore the call. If the “Allow Barge-In” 
parameter is enabled, the RTP multicast call barges in, and any existing calls are 
put on hold. 
If an RTP multicast session already exists on the phone, and the phone receives 
another incoming RTP multicast session, the priority is given to the first multicast 
session and the second multicast session is ignored. The behavior for the 
incoming calls in this case is also based on the setting for the “Allow Barge-in” 
parameter. The incoming call is handled as if there were an existing call already 
on the phone.
Note: 
Multicast RTP is one way only - from sender to the receiver (i.e. 
from sender to the multicast address(es) (receiver)). 
Note: 
For outgoing RTP multicasts, all other existing calls on the phone 
are put on hold.
Draft 1