Paging
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Purpose
Paging means a one-way audio communication from one caller to a potentially large group of listeners. Typical applications include supermarkets, hospitals or trains. You may have several paging groups on one PBX that addresses different audiences. For example, you might have one paging account that calls a specific floor of the building, and you might have another group that pages the whole building.
Intercom is a potentially two-way communication between two participants. Intercom is controlled by the feature codes Intercom. In the previous version of the PBX, those two features were both in the paging group. In this version, they have been separated.
There are two ways to implement paging. The first way establishes regular calls to the paging recipients by using standard SIP calls (indicating that the call should be immediately connected by auto answer). This method works with most available SIP phones and there is also special equipment available that works as an overhead paging speaker. However, when the paging groups become bigger, it puts a lot of performance load on the PBX CPU.
Therefore the PBX offers a second paging mode, which just sends the RTP traffic to a predefined RTP IP address. Typically this is an IP multicast group. Phones and other overhead paging equipment will subscribe to that multicast group and go to paging mode as soon as they receive RTP traffic on this port. Using this method, you can build up very large paging groups with hundreds and thousands of speakers distributed in the organization.
Identity
The paging account names may be changed after the creation just like you can change the name of an extension (settings "Primary Name" and "Alias Names"). See the documentation about the Extension Identity.
Unicast Mode
In unicast mode, you can list the destination extension numbers in the setting "Destination". Please be careful with the paging group size. The PBX must initiate a call to all of the listed extensions, and this may take significant CPU and bandwidth resources. Unicast paging is not limited to the local area network; all extensions that are connected to the PBX can be paged, no matter where they are located.
You must list the extensions that are allowed to page this group in the setting "Source". If you want to give access to all extensions, you may put a star into that field. When you enter a star into the settings, you may also call from a trunk to the paging account. Otherwise, you can use Wildcard Patterns to match a group of accounts.
- Entering a star ("*") into the setting will allow anyone to call the group, including calls from a trunk.
- Entering a list (separated by space) of patterns will check if the caller is a extension and the canonical extension name matches one of the list items. For example, if you enter "4* 5*" into the settings, the extensions "400", "401", "440", "550" will match, while "301" and "702" will not match.
- You can also just list the extensions that have permission to call the extension. If you use a list like "401 402 403" then only these three extensions will be allowed to call the group.
The "Display Name" will be used as the "From" of the call, so that the SIP phones will show this text in the display during the paging. You can use a name like "PA" (Public Annoucement) in the display. The name will only be shown on unicast calls (multicast does not use SIP).
Dialog Permissions are described in Dialog Permissions.
Multicast Mode
In multicast mode, you must specify one IP address in the form x.x.x.x:n (IP address with port). You can use only one IP address. You can either specify a regular IP address or a multicast address (for more information about multicast, see http://en.wikipedia.org/wiki/IP_Multicast).
It is up to you which IP address you use as the destination. You may use a multicast IP address (typically starting with 224.x.x.x), but you can specify any IP address there. For example, if you are using one paging device that is running on a specific IP address and port, you can specify the IP address and port of that device. For example, the paging output connector of the CS410 is running the IP address 1.1.1.2:2048, which is a simple unicast address.
The IP address and the port must match the address and the port of the destination device. Either you set this up manually on the paging device or you use the automatic provisioning of endpoint to set this up automatically.
The meaning of the "Source" and the "Dialog Permission" are the same as in unicast mode.
