The Push To Talk (PTT) service allows a user to call another station, where the system requests that the destination station automatically answer (go off hook.) This provides for intercom-like functionality. A user or administrator can specify an accept list and a reject list. These are used to screen incoming Push-To-Talk sessions.

• The accept list indicates which users are allowed to call a station.
• The reject list indicates which users are not allowed to call a station.

In both lists, a wildcard can be used, which indicates all stations.

Using Push-To-Talk
Making calls (Origination)
A user originates a PTT call by dialing the PTT FAC(*50). If the users do not supply a destination address when dialing the PTT FAC, then they are given stutter dial tone so that they can enter the destination address for the PTT call.

• If no destination address is entered (that is, digit collection times out), then the call is sent to reorder treatment.
• If a destination address is provided, then a PTT call is originated to the destination address.

NOTE: The PTT origination is processed by the user's origination services such as the Outgoing Calling Plan. When the originator of a PTT call receives an indication that the call has been answered, a PTT confirmation tone (BEEP) is played to both the originator and terminator. Once the confirmation tone has finished playing, the media path between the originator and terminator is established according to the Outgoing Connection Type. If the user has the Outgoing Connection Type option set to One-Way, then no media can be transmitted from the terminator to the originator, after the call is answered. Only the originator is allowed to transmit media. If the terminator answers the call to play treatment, the originator will not hear the treatment since the call has been answered and the connection is now one-way.
NOTE: Before answer, the connection is always two-way so that remote media (such as remote ringback and early treatment) can be heard prior to answer. If the Outgoing Connection Type option is set to Two-Way, then the originator and terminator can talk to each other as usual.

Push-To-Talk Termination
When users receive a PTT call, it is screened using their Access List according to the Access List type setting. If the Access List type option is set to "Allow calls from only the users selected below" (that is, an Accept List), then the PTT call is rejected with the PTT Rejected announcement, if the originator is not in the Access List. If the Access List type option is set to "Allow calls from everyone except the users selected below" (that is, a Reject List), then the PTT call is rejected with the PTT Rejected announcement, if the originator is in the Access List. Note that the Access List in this release can only contain other users in the group and/or enterprise. If the terminator has the Access List set to be an Accept List, then all PTT calls from outside the group and enterprise are rejected since the originator cannot be in the list. Similarly, if the terminator has the Access List set to be a Reject List, then all PTT calls from outside the group and enterprise are accepted since the originator cannot be in the list. If the user's Access List allows the PTT call, then it is allowed to continue. If the Auto- Answer option setting is set to "On", then a header like the following is added to the INVITE(s) sent to the user's SIP device: Call-Info:;answer-after=0 This header is defined in the Broadcore Advanced Call Control Specification and indicates that the device should immediately answer the call. If the device supports the header, then the PTT call is automatically answered. If the device doesn't support the header, then the PTT call must be manually answered. Note that if the terminating user does not have the PTT service assigned, then an incoming PTT call is treated as a normal call termination instead of a PTT termination (for example, no Auto-Answer, no Access List screening), but continues to be considered a PTT call for service interactions.

Configuration
The PTT service is a user service. Therefore, it can be authorized to service providers/enterprises and groups, and can be assigned to users. There are several configurable options for the PTT service. All are configurable by both administrators and users. The Outgoing Connection Type option can be set to One-Way or Two-Way. When set to One-Way, only the originator of a PTT call can talk. When set to Two-Way, both the originator and terminator of a PTT can talk. Its default setting is Two-Way. The Auto-Answer option can be set to "On" or "Off". When users receive a PTT call with Auto-Answer set to "On", their device is signaled to automatically answer the call. Its default setting is "On". The Access List type option can be set to "Allow calls from only the users selected below" (that is, an Accept List) or "Allow calls from everyone except the users selected below" (that is, a Reject List). Its default setting is "Allow calls from only the users selected below". The Access List itself is a list of users within the PTT user's Group and/or Enterprise (if the user is a member of an Enterprise). Users can be searched for, added to, and removed from the Access List. The Access List is used as defined by the Access List type option. At the group and service provider/enterprise levels, the PTT FAC can be configured by administrators. It defaults to *50, but can be changed to any valid, available FAC.

How to:
The original setup should be done by the administrator. And once it is set up the user can make changes to allow or restrict with whom they can Push to Talk. From your personal web portal. Click on Call Control. Click Push to Talk.

The setting options are:
Auto-Answer On or Off
Outgoing Connection Type: One-Way or Two-Way
Access List: Allow calls from only the users selected below or Allow calls from everyone except the users selected below

And then choosing names below by clicking Search and moving them from the left column to the right column.
Click OK or Apply to save.