Call Control

Chapter 6 Integrating Cisco Unity with the Phone System

Sample Path for a Call from the Phone System to a Subscriber

If the phone system sends the necessary information and if Cisco Unity is configured correctly, an integration can provide the following integration functionality:

•Call forward to personal greeting

•Call forward to busy greeting

•Caller ID

•Easy message access (a subscriber can retrieve messages without entering an ID because Cisco Unity identifies the subscriber based on the extension from which the call originated; a password may be required)

•Identified subscriber messaging (Cisco Unity identifies the subscriber who leaves a message during a forwarded internal call, based on the extension from which the call originated)

•Message waiting indication (MWI)

The phone system uses a set of signals to set up, monitor, and release connections for a call. Cisco Unity monitors call control signals to determine the state of the call, and uses these signals to respond appropriately to phone system actions and to communicate with the phone system. For example, a caller who is recording a message might hang up, so Cisco Unity detects that the call has ended and stops recording.

Depending on the phone system, the following types of call control signals are used:

Cisco Unified	For Skinny Call Control Protocol (SCCP) integrations, Cisco Unified
Communications	Communications Manager generates SCCP messages, which are translated by the
Manager	Cisco Unity-CM TSP into TAPI that Cisco Unity uses. Cisco Unity
	actions—such as hook flash for transferring calls—are translated by the
	Cisco Unity-CM TSP into the SCCP messages that Cisco Unified CM uses.
	For SIP trunk integrations, Cisco Unified CM sends SIP messages, and
	Cisco Unity sends SIP responses when a call is set up or terminated.

Circuit-switched	For PIMG/TIMG integrations, the phone system sends messages to the PIMG or
phone system	TIMG units, which send the applicable SIP messages to Cisco Unity. Cisco Unity
	sends SIP responses when a call is set up or terminated, and the PIMG or TIMG
	units communicate with the phone system.
	For voice card integrations, the phone system generates and responds to in-band
	signaling (for example, busy, disconnect, DTMF, and hook flash). The signaling
	tones are translated by the Dialogic TSP into TAPI events that Cisco Unity can
	use. Cisco Unity makes a telephony request such as “transfer,” which is translated
	by the Dialogic TSP into the signal (hook flash) that the phone system can use.

Sample Path for a Call from the Phone System to a Subscriber

The following steps give an overview of a sample path that an external call can take when traveling from the phone system to a subscriber.

1.For Cisco Unified Communications Manager, when an external call arrives, the gateway sends the call over the LAN or WAN to Cisco Unified CM.

Design Guide for Cisco Unity Release 5.x

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