Cisco Systems 5.x manual Do not convert outbound messages, Do not convert incoming messages

Chapter 8 Using VPIM for Networking with Cisco Unity Express or Other Cisco Unity Systems

Messaging Between Cisco Unity Servers in Different Directories

Example 3: One Cisco Unity Server Uses G.711 and the Other Uses G.729a

Consider the case where one Cisco Unity server uses G.711 for recording and storage and the other uses G.729a. If network bandwidth is not an issue:

On the Cisco Unity server that uses G.711	• Do not convert outbound messages.
	• Do not convert incoming messages.
On the Cisco Unity server that uses G.729a	•	Do not convert outbound messages.
	•	Do not convert incoming messages.

Cisco Unity can transcode messages recorded and stored in multiple formats, so the best option is to not convert outbound or incoming VPIM messages. This approach avoids the overhead of audio format conversions.

If network bandwidth is an issue, and you want to continue recording messages in G.711:

On the Cisco Unity server that uses G.711	• Convert outbound messages to G.726. This resolves the
	network bandwidth issue because the outbound messages
	will be sent in the G.726 32Kbps format, which is half the
	size of G.711 messages.
	• Do not convert incoming messages. In general, if a
	message is recorded and stored in a lower quality codec,
	and then later converted to a higher quality codec, the
	sound quality does not improve, so there is no benefit to
	converting the incoming G.729a messages to G.711.
On the Cisco Unity server that uses	• Do not convert outbound messages. At 8Kbps, the G.729a
G.729a	is the best codec to use when there are network bandwidth
	issues.
	• For incoming messages, your options are:
	– Convert incoming messages to G.729a. Although this
	results in an additional audio format conversion,
	presumably all subscriber workstations are already
	configured for G.729a, because that is the codec used
	by the Cisco Unity server.
	– Do not convert incoming messages, and leave them in
	G.726. Although this avoids another conversion,
	G.726 is not supported as a region (line) format for a
	Cisco Unified Communications Manager integration.
	Also, if VPIM messages are stored in G.726, all
	Cisco Unity servers and subscriber workstations must
	have the G.726 codec installed.

Networking Guide for Cisco Unity Release 5.x (With Microsoft Exchange)

OL-13844-01 8-5