Cisco Unity: CUCM Integration

Cisco Unity can be integrated with Cisco Unified Communications Manager over IP infrastructures using Cisco’s proprietary Skinny Client Control Protocol (SCCP) or Session Initiation Protocol (SIP). Cisco Unity can also be integrated with legacy voicemail solutions via PIMG (PBX IP Media Gateway) or TIMG (TDM IP Media Gateways) devices. Earlier versions of Cisco Unity supported Dialogic PCI expansion cards for traditional (TDM) PBX integrations, but Cisco stopped supporting the Dialogic PCI cards beginning with their support of the Windows 2003 server operating system. Cisco does not support Unity 5.x or 7.x installations on Windows 2000 server. Let’s take a look at how a call is handled from the PSTN to the Cisco Unity voicemail system. A call is placed from the PSTN to the direct inward dialing (DID) phone number of a Cisco IP Phone. The call is received at an MGCP gateway controlled by CUCM configured with a number of significant digits that matches the internal abbreviated dial plan of five digits. CUCM performs the digit analysis of the incoming call within the context of the incoming Calling Search Space (CSS) applied to the gateway. Assuming the CSS includes the partition of the internal phone number being dialed, the Cisco IP Phone begins to ring. If the IP Phone is busy or not answered, the directory number is configured to forward the call to voicemail. The directory number of the Cisco IP Phone is configured with a voicemail profile. The voicemail profile is associated with a Voice-Mail Pilot Number. The Voice-Mail Pilot Number can include a Calling Search Space (CSS) which needs to have access to the route partition the Hunt Pilot is configured in. The Hunt Pilot is used for call coverage capabilities in CUCM. The hunt pilot in this application will be used to distribute calls to available voice mail ports. The call coverage processing path in CUCM is as follows: Hunt Pilot (HP) > Hunt List > Line Group > Voicemail port. The configuration order is bottom up as described in the next paragraph. Voice mail ports are configured in CUCM and added to a Line Group. The Line Group is configured with a Top Down distribution algorithm which includes the voice mail ports of the primary Unity server. A Hunt List is configured and pointed to the primary unity server Line Group. If the licensed failover feature is used, a second Line Group would be configured with the backup Unity server and added to the Hunt List as a secondary option. The backup Unity server is accessed if the primary Unity server stops answering calls. A Hunt Pilot is configured and pointed to the Hunt List. The technical details of the above two paragraphs, can be summarized as follows: CUCM routes call forward busy (CFB) and call forward no answer (CFNA) conditions to the Cisco Unity server over an IP infrastructure. Skinny Client Control Protocol (SCCP) is used as a signaling protocol from CUCM to Cisco Unity. The Cisco Unity server uses a TSP (TAPI service provider) to convert the Skinny signaling from CUCM to TAPI (Telephony API) and MAPI (Messaging API) calls. TAPI is used to convert SCCP signaling to the information store (IS). The information store (or SQL server database) has all of the configuration date of Cisco Unity (subscribers, call handlers, etc.). The message store (Microsoft Exchange or IBM Informix Database) is responsible for storing voicemail messages. In the next blog, we will delve into more details of the CUCM and Unity integration. References: Unity Install and Upgrade Guides (all versions): http://www.cisco.com/en/US/products/sw/voicesw/ps2237/prod_installation_guides_list.html Unity Maintain and Operate Guides (all versions): http://www.cisco.com/en/US/products/sw/voicesw/ps2237/prod_maintenance_guides_list.html TSP Release Notes http://www.cisco.com/univercd/cc/td/doc/product/voice/c_unity/tsp/index.htm TIMG Integration Guide http://www.cisco.com/en/US/docs/voice_ip_comm/unity/5x/integration/timg/guide/cuinttimg.html PIMG Integration Guide http://www.cisco.com/en/US/prod/collateral/voicesw/ps6789/ps5745/ps2237/product_data_sheet0900aecd80106ee5.html