Voice Mail Networking

Cisco UE release 2.0 introduced basic voice mail networking between systems using blind addressing, and release 2.1 enhances this functionality with spoken-name and limited dial-by-name addressing using a local directory and cache. You can network voice mail messaging between Cisco UE systems at different sites, as well as with Cisco Unity systems, using Voice Profile for Internet Mail (VPIM) connectivity between the systems. Cisco UE does not support networking with any voice messaging systems other than Cisco UE and Cisco Unity systems.

You can configure Cisco UE networking using either Domain Name System (DNS) host names or explicit IP addressing. If you are networking with a Cisco Unity system, you must use a DNS configuration.

The following sections provide a brief overview of Cisco UE voice mail networking operation, including the following topics:

• Applicable standards
• Definition of network locations
• Voice mail network location addressing
• Directories
• Network broadcast messaging
• Message formats
• Nondelivery notification

Standards

Voice mail networking uses the following Internet Engineering Task Force (IETF) standards:

• RFC 3801, Voice Profile for Internet Mail - Version 2 (VPIMv2)
• RFC 2821, Simple Mail Transfer Protocol (SMTP)
• RFCs 20452049, Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies
• RFC 822, Standard for the Format of ARPA Internet Text Messages

The Simple Mail Transfer Protocol (SMTP) and Multipurpose Internet Mail Extension (MIME) protocols are the basic protocols used to send and receive e-mail. Voice mail networking leverages the exact same protocols and infrastructure. The primary attributes of a voice mail (compared to an e-mail) are the address (voice mail uses a phone number and e-mail uses a user ID) and the message's payload type (voice mail uses an encoded form of a .wav file, and e-mail uses other formats, including text).

Cisco Unity is a unified messaging system and provides both voice mail and e-mail networking. Cisco UE (up to release 2.1) is only a voice messaging system. It does not provide any way to address, send, or receive e-mail messages.

Although Cisco UE's voice mail networking implementation is compliant with the VPIM standard, the entire RFC is not supported. Cisco UE and Cisco Unity also implement some extensions to VPIM to provide features such as broadcast messaging between sites that are not specified by the standard.

You can find more information on Internet Engineering Task Force (IETF) standards at http://www.ietf.org/.

Locations

You can enable voice mail networking by configuring the parameters of the locations in the network, including the local location and all remote locations that this site can exchange messages with. The network has no central directory or proxy location. Each Cisco UE site must be configured with the identities of the other locations in the network that it can send messages to or receive messages from. For security reasons, Cisco UE does not accept (receive) messages from any sites other than those configured in its database as a valid networking location.

Each location is defined in the Cisco UE configuration with the following parameters:

• ID A unique one- to seven-digit numeric identifier assigned to each site. The location ID is a sequence of digits that must be dialed before the extension when addressing a message to a remote site via the TUI. It is only locally significant (to select which remote site is being addressed) and is not sent with the VPIM message.
• Abbreviation A one- to five-character alphanumeric abbreviated name for the location. This is spelled to the user as part of address confirmation if a spoken name for the location was not recorded or is unavailable.
• Name A one- to five-character descriptive name for the location. Used only for human readability of the configuration information.
• Extension Length The number of digits in extensions at this location. Used for a level-of-error checking in blind addressing.
• Domain Name of IP Address This part of the address appears after the @ when messages are addressed. For example, for the VPIM address [e-mail], site2.xyz.com is the domain name. This can be a DNS host name or an explicit IP address.
• Phone Number Prefix (optional) A digit prefix added to the extension number to ensure that VPIM addresses are unique in the network. If your extensions are already unique (nonoverlapping), you generally do not have to configure this field. You can use the field to do a limited amount of digit manipulation on the extension portion of the VPIM address. Phone prefixes are prepended to the extension by the sending location and are removed from the address by the receiving location. Phone prefixes apply to both the To and From address fields in the VPIM header.
• Spoken Name (optional) Specifies whether to send the spoken name of the voice mail originator as part of the VPIM message. If the spoken name is sent, it is played as the first part of the message envelope to the recipient. This feature is enabled by default.
• Message Encoding (optional) Configures the encoding method used to send voice mail messages to this location. This is discussed further in the later section "Message Formats."

As soon as you have defined all the locations in the configuration, you indicate which one of these locations represents your local system by configuring the local location ID to match one of the locations in the list. A configuration with five sites is shown in Example 10-11. You can view this same configuration in the GUI by navigating to the Administration > Networking Locations screen. The local location is ID 888. This exact same configuration also appears in sites 222, 333, 444, and 666, except that their local location IDs are indicated as 222, 333, 444, and 666, respectively.

Example 10-11. Network Location Configuration

cue#show network locations
ID NAME ABBREV DOMAIN
222 'Site2' S2 site2.xyz.com
333 'Site3' S3 site3.xyz.com
444 'Site4' S4 site4.xyz.com
666 'Site6' S6 site6.xyz.com
888 'Site8' S8 site8.xyz.com
Local location id: 888 

Example 10-12 shows the full configuration parameters of site 888 from the configuration summary in Example 10-11.

Example 10-12. Site8 Networking Parameters

cue#show network detail local
Location Id: 888 
Name: Site8
Abbreviation: S8
Email domain: site8.xyz.com
Minimum extension length: 4
Maximum extension length: 4
Phone prefix:
VPIM encoding: dynamic
Send spoken name: enabled
Send vCard: enabled
State: enabled
VPIM broadcast ID: vpim-broadcast

Up to 500 sites may be defined on a Cisco UE system for voice mail networking.

Addressing

A voice message to another site can be addressed in one of the following methods:

• Blind addressing The sender explicitly specifies the location ID and the recipient's extension at that location.
• Spell-by-name The spell-by-name message sends facility searches for matches in both the local Cisco UE user directory and the remote user information available in the sender's local system directory, as described in the next section.
• Spell-by-location If a sender uses the spell-by-name feature, but the name spelled matches a location name instead of the name of subscriber, the sender is prompted to add the recipient's extension digits to complete the addressing.

As the Cisco UE system administrator, you can record spoken names for remote locations so that when a subscriber addresses a message to a remote location, the address confirmation is not just simply numeric or the spelled-out abbreviation you configured, but plays the recorded name associated with that location. For example, if a sender on Site2 addresses a message to extension 4001 at Site4, the address confirmation he or she hears says "San Jose" as opposed to just "444" or "S-4." You can record these spoken names to make it as easy as possible for your subscribers to address messages correctly.

Directories

Cisco UE keeps a small amount of information on remote users to aid in spoken-name confirmation during message addressing at the sending location. The Cisco UE system reads the remote user's location ID and extension by default as the address confirmation to the local sender during the message addressing step. If a spoken name has been recorded for the remote location, it is played instead of the location ID. If the remote user's spoken name exists in the networking directory on the sender's local system, it is played instead of the extension.

A Cisco UE system keeps the following two local directories of information about remote users to provide spell-by-name and spoken-name confirmation support during a subscriber message send activity:

• Static directory This directory is populated explicitly by the administrator with the names and extensions of frequently addressed remote users. You can enter this configuration by using the Configure > Remote Users GUI screen or the remote username CLI command.
• Cache A least-recently-used (LRU) cache of entries is kept, dynamically populated by the names on the incoming voice messages received by this Cisco UE system.

Messages sent by Cisco UE contain vCard information. On the receiving system, the Vcard information on an incoming voice message is used to populate or refresh the information in the local and LRU cache directories.

The static directory and the LRU cache each have a capacity of 50 user entries on an NM-CUE and 20 entries on an AIM-CUE.

Network Broadcast Messages

Cisco UE supports sending broadcast messages to remote sites. All remote sites or a subset of remote sites can be selected in the addressing of a broadcast message. If a broadcast message is sent to a remote site, all users at that site receive the message.

Message Formats

The VPIM specifies G.726 (32K adaptive differential pulse code modulation [ADPCM]) encoding. Cisco UE supports two formats of message encoding, which can be selected in the configuration of each site:

• G.726 Messages are converted to G.726 for transmission to a remote system. Although this format uses half the bandwidth of the G.711 format, VPIM voice messages are sent like e-mails (which means best-effort, non real-time-sensitive traffic), and bandwidth typically is not a concern.
• G.711 Messages are sent as .wav file format to the remote system. This format reduces the overhead of encoding and decoding messages between systems. This format is used when exchanging messages between two Cisco UE systems.

When you configure the message encoding for a Cisco UE site, you can choose either of the two methods explicitly, or you can use the default setting, which is dynamic. This was shown earlier in Example 10-12 as the VPIM encoding field. The dynamic option means that Cisco UE automatically determines which of the two formats to use. If the destination system is another Cisco UE, it uses the G.711 format. If the destination system is a Cisco Unity system, it uses the G.726 format.

If you configure the encoding method explicitly, Cisco UE always sends messages in the configured format to the corresponding remote site. When configured with the dynamic option, Cisco UE sends messages based on the capabilities advertised by the remote system in the SMTP session setup.

Nondelivery Notification

Cisco UE attempts to send a message to a remote destination immediately. If it isn't successful, it retries every 15 minutes for 6 hours. If a message cannot be delivered during this time, a notification is returned to the sender and is placed in the sender's voice mailbox. This notification appears as a new message and informs the sending subscriber of a delayed delivery. Similarly, if the message cannot be delivered for reasons such as the recipient's mailbox is full, does not exist, or is disabled, an NDR is placed in the sender's mailbox along with a copy of the original message. When the subscriber plays the NDR, he or she can readdress and resend the message or delete it.

If Cisco UE is unable to create an SMTP session for one day to deliver remote messages, an NDR message is returned to the message sender, as well as to the administrator's mailbox to inform him or her of a networking problem.

Voice Mail Deployment Considerations