Reference Guide
© 2009 Cisco Systems, Inc. All rights reserved. This document is Cisco Public Information.
Page 6 of 11
Table 8.
DSP Resource Utilization on the Cisco UC 540
Feature
DSP Resource Utilization
Support for built-in FXS ports
4 channels
Support for built-in FXO ports
4 channels
Support for built-in music on hold (MoH) port
2 channels
Support for T1/E1 voice/WAN interface card (VWIC)
24 channels*
Transcoding (g711 to g729)
2 channels
Conferencing**
16 channels
* Total DSP resources will depend upon the number of channels provisioned in the T1.
** Conferencing always uses up an entire DSP. The rest of the features can share a DSP. The number of sessions available will
vary depending upon the codec used in a conference call.
Tables 9 and 10 list maximum sessions for either ad hoc conferencing or meet-me conferencing. DSP resources
allocated for conferencing can be shared by both features, and a mix of these can be configured. Below are a few
examples based on Table 9. The concept of sharing conferencing resources applies to Table 10 as well.
Ad hoc 24x8
Meet-me 0x0
Ad hoc 12x8
Meet-me 12x8
Ad hoc 24x4
Meet-me 6x16
The above examples indicate Sessions x participant.
The Transcoding column lists the maximum transcoding sessions that the system can be configured for, for a given
configuration of DSP. For example, the first row in Table 9 indicates that a maximum of three transcoding sessions
are available if three DSPs are allocated for conferencing.
If more transcoding sessions are required, DSP resources will need to be diverted from conferencing to transcoding.
For example, in the second row of Table 9, one of the DSPs is dedicated to transcoding, leaving two DSPs for
conferencing. Notice the increase in the number of transcoding sessions and the drop in the number of conferencing
sessions.
Table 9.
DSP Resources: Scenario 1
UC 500
Model
Additional
Voice Card
(VIC)
SIP Trunk
Preferred Codec
Ad-hoc
Conference
(Sessions x
Participants)
Meet-me
Conference
(Sessions x
Participants)
Comments
Transcoding
No SIP Trunk or
G.711
Up to a maximum
of 24x8 or 48x4
Up to a maximum
of 24x8 or 12x16
or 6x32
●
1 DSP for supporting voice ports and Transcoding
sessions
●
Remaining 3 DSPs used for Conferencing
A maximum of 3
Transcoding sessions for
this configuration
None
G.729
Transcoding
sessions
recommended
Up to a maximum
of 4x8 or 8x4
Up to a maximum
of 4x8 or 2x16 or
1x32
●
1 DSP for supporting voice ports and Transcoding
sessions
●
1 DSP reserved for transcoding
●
Remaining 2 DSPs used for Conferencing
A maximum of 11
Transcoding sessions for
this configuration
No SIP Trunk or
G.711
Up to a maximum
of 24x8 or 48x4
Up to a maximum
of 24x8 or 12x16
or 6x32
●
1 DSP for supporting voice ports and Transcoding
sessions
●
Remaining 3 DSPs used for Conferencing
A maximum of 2
Transcoding sessions for
this configuration
2FXS
2FXS/DID
2FXO
G.729
Transcoding
sessions
recommended
Up to a maximum
of 4x8 or 8x4
Up to a maximum
of 4x8 or 2x16 or
1x32
●
1 DSP for supporting voice ports and Transcoding
sessions
●
1 DSP reserved for transcoding
●
Remaining 2 DSPs used for Conferencing
A maximum of 10
Transcoding sessions for
this configuration
No SIP Trunk or
G.711
Up to a maximum
of 24x8 or 48x4
Up to a maximum
of 24x8 or 12x16
or 6x32
●
1 DSP for supporting voice ports and Transcoding
sessions
●
Remaining 3 DSPs used for Conferencing
A maximum of 1
Transcoding sessions for
this configuration
UC 540
4FXS
4FXS/DID
4FXO
2BRI NT/TE G.729
Transcoding
Up to a maximum
of 4x8 or 8x4
Up to a maximum
of 4x8 or 2x16 or
●
1 DSP for supporting voice ports and Transcoding
sessions
A maximum of 9
Transcoding sessions for
