Multicast paging is an approach to let different SIP users to listen to a page from a common multicast IP address. In a multicast page call, one-way audio will be setup from sender to listeners, but the listeners cannot talk to each other. The sender and listeners must be located within the same LAN.
GXP21xx/17xx/16xx supports multicast page sending and listening on firmware version 1.0.4.10 or greater. Users could configure line keys, Virtual Multi-Purpose keys, or multi-purpose keys to send multicast paging. Also, GXP21xx/17xx/16xx is capable to listen to at most 10 different multicast addresses by following defined preferences.
This document serves as an end-user guide on how to configure the multicast page on the GXP21xx/17xx/16xx.
SENDING MULTICAST PAGING
Configuration
Sender multicast page configurations are under GXP21xx/17xx/16xx’s Web UI Settings > Programmable Keys > Virtual Multi-Purpose Keys OR Multi-Purpose Keys.
- Set the key Mode to Multicast Paging in dropdown list.
- Enter the multicast paging description in Description field.
- Enter multicast paging address and port in Value field.
The range of multicast page addresses is 224.0.0.0 to 239.255.255.255 with a port not in use by phone.
The figures below show the example of setting Line Keys/MPK to multicast page sending key.


GXP21xx/17xx/16xx supports 5 codecs for Multicast Paging. User can specify the multicast page sending codec under Web GUI Settings > Multicast Paging > Multicast Paging Codec. The supported codecs are PCMU, G.729A/B, PCMA, G.726-32 and G.722.
Send Multicast Paging Call
After configuring the sender multicast page, users could make a multicast page to remote parties.
- Press the configured MPK/VPK or Line Key to send a multicast page.
The LED light of the key will turn green, and the phone screen will show the multicast address with the defined label.
- Press the “EndCall” soft key to end the multicast paging.

RECEIVING MULTICAST PAGING
Configuration
To receive a multicast page, GXP21xx/17xx/16xx must be well configured to listen to the right address and port. The configurations are under Settings > Multicast Paging. There is 10 listening addresses supported with priority levels 1 to 10. Optionally, each of these addresses can also have a label that will display on LCD when the page is received.

Paging Barge | Assigns any number from 1 to 10. When enabled, during the active call if the incoming multicast page is higher than this value, the call will be held, and the multicast page will be played. |
Paging Priority Active | If enabled, during a multicast page if another multicast is received with higher priority that one will be played instead.
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Multicast Paging Codec | The codec for Multicast page sending. The default setting is PCMU. G.729A/B, PCMA, G.726-32, and G.722 (wideband) are supported as well. |
Multicast Listening | Support 10 of listening multicast addresses with priority levels 1-10 with 1 being the highest priority. The lower the level, the higher the priority. |
Paging Barge
This option is to control the priorities between multicast pages and common SIP calls. Available options are Disabled and numbers 1 to 10. If the option is set to disabled then all incoming pages are ignored while in a call.
When the option is set to a number, Paging Barge is enabled. If the number of Paging Barge is higher than an incoming page’s priority value (determined by the position in the list 1-10) then the incoming page is not played. Similarly, if the Paging Barge value is lower than an incoming page’s priority value, and then the active SIP call will be held.
As an example, in Figure 3, the Paging Barge is configured as 3. During an active call, if incoming multicast page priority is greater or equal to 3, the currently active call will be held, and the page will be played. However, if the incoming multicast page priority is 1 or 2, the currently active call will be kept.
Paging Priority Active
This option is to control the priorities among different multicast pages. If the option is disabled, the phone ignores any incoming pages when a page is already being played. Otherwise, incoming pages with a higher priority will be played instead of the current page. For example, if the phone is playing a page whose priority is 5 and there is an incoming page with priority 3, the priority 5 page will stop and the priority 3 page will play instead.
Receive Multicast Paging Call
After multicast page listening is well configured, please reboot the phone to let the settings take effect. When there is a page on the listening address and port, the phone will play the incoming audio automatically. Users can press the “EndCall” soft key to end the page.