SIP User's Manual 260 Document #: LTRT-65415
MediaPack Series
8.2.7.5.1 Call Forward Reminder Ring
The device supports the Call Forward Reminder Ring feature for FXS interfaces, whereby
the device's FXS endpoint emits a short ring burst (only if in onhook state) when a third-
party Application Server (e.g., softswitch) forwards an incoming call to another destination.
This is important in that it notifies (audibly) the FXS endpoint user that a call forwarding
service is currently being performed.
Figure 8-16: Call Forward Reminder with Application Server
The device generates a Call Forward Reminder ring burst to the FXS endpoint each time it
receives a SIP NOTIFY message with a “reminder ring” xml body. The NOTIFY request is
sent from the Application Server to the device each time the Application Server forwards an
incoming call. The service is cancelled when an UNSUBSCRIBE request is sent from the
device, or when the Subscription time expires.
The Reminder Ring tone can be defined by using the parameter CallForwardRingToneID,
which points to a ring tone defined in the Call Progress Tone file.
The following parameters are used to configure this feature:
EnableNRTSubscription
ASSubscribeIPGroupID
NRTRetrySubscriptionTime
CallForwardRingToneID
8.2.7.5.2 Call Forward Reminder (Off-Hook) Special Dial Tone
The device plays a special dial tone (Stutter Dial tone - Tone Type #15) to a specific FXS
endpoint when the phone is off-hooked and when a third-party Application server (AS),
e.g., a softswitch is used to forward calls intended for the endpoint, to another destination.
This is useful in that it reminds the FXS user of this service. This feature does not involve
device subscription (SIP SUBSCRIBE) to the AS.
Activation/deactivation of the service is notified by the server. An unsolicited SIP NOTIFY
request is sent from the AS to the device when the Call Forward service is activated or
cancelled. Depending on this NOTIFY request, the device plays either the standard dial
tone or the special dial tone for Call Forward.
For playing the special dial tone, the received SIP NOTIFY message must contain the
following headers:
From and To: contain the same information, indicating the specific endpoint
Event: ua-profile