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Chapter 8 Using VPIM for Networking with Cisco Unity Express or Other Cisco Unity Systems
Messaging Between Cisco Unity Servers in Different Directories
Figure 8-3 No Audio Format Conversions
Example 2: Both Cisco Unity Servers Use G.711 for Recording and Storage
It is also possible for both the local and remote Cisco Unity servers to record messages by using the
G.711 codec. At 64 Kbps, messages encoded by using the G.711 codec are very high quality, but because
of their size, the messages may present a problem if network bandwidth is a concern. In this case, you
have the following options:
• Do not convert outbound and incoming VPIM messages, but monitor the network for problems.
Sending VPIM messages in the G.711 format may not turn out to b e an iss ue, particularly if message
traffic between the sites is light.
• Configure each server to convert outbound messages to G.726, and convert incoming messages back
to G.711. At 32 Kbps, messages encoded by using the G.726 codec are half the size of those encoded
by using G.711. The downside to this approach is that it results in two audio format conversions for
each VPIM message. This is extra work for the Voice Connector. In addition, when incoming
messages are converted back to G.711, there may be a loss in sound quality.
• Configure each server to convert outbound messages to G.726, but not to convert incoming
messages. This approach solves the network bandwidth concern and results in only one audio format
conversion for each VPIM message. However, G.726 is not supported as a region (line) format for
a Cisco Unified Communications Manager (CM) (formerly known as Cisco Unified CallManager)
integration. Also, if VPIM messages are stored in G.726, all Cisco Unity servers and subscriber
workstations must have the G.726 codec installed. (The G.726 codec is installed on the Cisco Unity
server during setup.)
• Change the codec that will be used by the Cisco Unity servers to record messages from G.711 to
G.729a, and do not convert the audio format of VPIM messages.
ParisUnity
NewYorkUnity
Dial ID: 333
Domain Name: paris.cisco.com
Audio Format Conversion:
Do Not Convert Outbound Messages
Do Not Convert Incoming Messages
VPIM Delivery Location
Dial ID: 444
Domain Name: ny.cisco.com
Audio Format Conversion:
Do Not Convert Outbound Messages
Do Not Convert Incoming Messages
VPIM Delivery Location
Internet
G729a G.729a
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