Supplementary Services Features for FXS Ports on Cisco IOS Voice Gateways Configuration Guide, Cisco IOS Release 15M&T

Feature Summary

Table 1 contains information about SCCP-based CallBack on No Answer for Analog Phones on Cisco Voice Gateways, along with information about how to configure support for this feature in your Cisco call-control system.

Table 1 CallBack on No Answer for Analog Phones

CallBack on No Answer for Analog Phones

When the analog FXS ports are enabled by the Skinny Client Control Protocol (SCCP) telephony control (STC) application (STCAPP), calls through the FXS endpoints are controlled by the Cisco Unified CM, with basic call support in Survivable Remote Site Telephony (SRST) mode. The STCAPP on the Cisco voice gateway functions as a proxy to translate call-control messages between the Cisco call-control system and the voice gateway.

The Cisco Unified CM monitors the called telephone when you activate the CallBack feature on an analog phone when the remote side is either not answering the phone or is busy. For more information, see the “Configuring CallBack on Busy” section.

When the called telephone becomes available to receive a call, the Cisco Unified CM verifies that the calling phone is also available and if so, automatically activates the CallBack notification. The original calling phone generates a special CallBack ringtone. When the calling party lifts the handset, the called phone receives a call as a regular call from the calling party.

Note Existing SCCP protocols for the CallBack feature are integrated with the IOS gateway and translated into analog phone tones and alert ringtones to support all phases of the CallBack scenario.

• In successful cases, the confirmation tone is used during CallBack activation. In cases where the Cisco Unified CM reports an error, a fast busy tone is played.
• If you activate the CallBack feature and go on-hook before the confirmation or error tones are played, you cannot determine whether the feature is activated successfully or not. If CallBack is activated, the scenario proceeds as usual and you hear the CallBack ringtone.

The following examples describe how CallBack on No Answer is supported on analog phones connected to IOS-based platforms, either on a call to another analog phone or to an IP phone:

• Normal Operation
• CallBack not completed because Calling Party does not answer
• CallBack not completed because Called Party does not answer
• CallBack not completed because Calling Party receives another incoming call

Note In the succeeding scenarios, A and B are both analog telephones existing in the same Cisco Unified CM Cluster connected to the same or different Cisco VG2nn Analog Gateway or Cisco ISR router. Alternatively, B can be any Cisco IP Phone existing in the same Cisco Unified CM cluster or any off-net phone, connected to Cisco Unified CM using Q Signaling PRI trunk.

User A calls user B, which does not answer (the phone rings).

User A hears ring back tone, then activates the CallBack feature by pressing #1 (configurable) and gets a confirmation tone from the system letting user A know that the feature has been activated. The system allows only one CallBack number to be activated at any time. If a CallBack to another destination is previously activated, it is automatically cancelled and replaced with the new destination.

User A is able to make calls to other users without affecting or cancelling the CallBack feature. The CallBack cannot be explicitly cancelled by the user.

When user B becomes available (by going on-hook), system checks if user A is also on-hook. If A is busy on another call, the system waits until both users A and B are available to establish CallBack call.

When both A and B are available (on-hook), user A receives the CallBack notification ringtone.

When user A lifts the handset he hears the CallBack ringtone and user B’s phone rings normally.

User A calls user B, which does not answer (the phone rings).

User A hears ring back tone, then activates the CallBack feature by pressing #1 (configurable) and gets a confirmation tone from the system letting user A know that the feature has been activated. The system allows only one CallBack number to be activated at any time. If a CallBack to another destination is previously activated, it is automatically cancelled and replaced with the new destination.

User A is able to make calls to other users without affecting or cancellingthe CallBack feature. The CallBack cannot be explicitly cancelled by the user.

When user B becomes available (by going on-hook), system checks if user A is also on-hook. If A is busy on another call, the system waits until both users A and B are available to establish CallBack call.

When both A and B are available (on-hook), user A receives a CallBack ringtone but does not answer.

The system keeps sending a CallBack ringtone to user A until the defined “ringing-timeout” set on the Cisco VG2nn Analog Gateway or Cisco ISR router is reached, if user A still does not answer, CallBack feature gets cancelled.

No further attempts to complete the call are made and there is NO notification to users about cancellation of the CallBack feature.

User A calls user B, which does not answer (the phone rings).

User A hears ring back tone, then activates the CallBack feature by pressing #1 (configurable) and gets a confirmation tone from the system letting user A know that the feature has been activated. The system allows only one CallBack number to be activated at any time. If a CallBack to another destination is previously activated, it is automatically cancelled and replaced with the new destination.

User A is able to make calls to other users without affecting or cancellingthe CallBack feature. The CallBack cannot be explicitly cancelled by the user.

When user B becomes available (by going on-hook), system checks if user A is also on-hook. If A is busy on another call, the system waits until both users A and B are available to establish CallBack call.

When both A and B are available (on-hook), user A receives the CallBack notification ringtone.

When user A lifts the handset he hears the CallBack ringtone and user B’s phone rings normally.

User B does not answer, the system keeps ringing B until the “No Answer Ring Duration” time (set in CUCM) is reached. If user B still does not answer, the CallBackfeature gets cancelled.

No further attempts to complete the call are made and there is NO notification to users about cancellation of the CallBack feature.

User A calls user B, which does not answer (the phone rings).

User A hears ring back tone, then activates the CallBack feature by pressing #1 (configurable) and gets a confirmation tone from the system letting user A know that the feature has been activated. The system allows only one CallBack number to be activated at any time. If a CallBack to another destination is previously activated, it is automatically cancelled and replaced with the new destination.

User A is able to make calls to other users without affecting or cancellingthe CallBack feature. The CallBack cannot be explicitly cancelled by the user.

When user B becomes available (by going on-hook), system checks if user A is also on-hook. If A is busy on another call, the system waits until both users A and B are available to establish CallBack call.

When both A and B are available (on-hook), user A receives the CallBack notification ringtone.

While user A hears CallBack ringtone, another incoming call comes in to A.

CallBack gets immediately cancelled and the ring pattern changes to normal.

When user A picks up the handset, the call is answered like a normal incoming call.

Note CallBack on No Answer requires additional effort in the activation phase since the activation happens at different call states.

In the case where call progress tones (busy or ringback) are coming in-band, possibly with some third party PBXs interconnected through Q Signaling trunks, the call goes to the “active” state, the media flows to the gateway, and the tones are delivered as part of media. In this case, CallBack is activate and works like a normal incoming call.

Configuring CallBack on No Answer for Analog Phones

Note This document does not contain details about configuring Cisco Unified CM. See the documentation for this product for installation and configuration instructions.

To modify the default values of the CallBack activation key sequence or ringing timer for CallBack on No Answer on analog phones on IOS-based platforms, perform the following steps on the Cisco voice gateway.

SUMMARY STEPS

1. enable

2. configure terminal

3. stcapp feature callback

4. activation-key string

5. ringing-timeout seconds

6. end

DETAILED STEPS

Example: Configuring Feature Callback in the STCAPP on a Cisco IOS Gateway

The following example shows a partial output of feature callback in the STCAPP on a Cisco IOS gateway with the key sequence for activating CallBack on No Answer defined as 1000 and the timeout period for the ringing timer defined as 10:

Example: Configuring CallBack on No Answer on a Cisco IOS Gateway

The following example shows how to configure CallBack on No Answer on a Cisco IOS gateway. In this configuration, the activation key and the timeout period for the ringing timer are modified from the defaults.

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