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NOTE: All values listed are the maximum for each function – you must mix & match to
get the optimum # of calls that can be supported over the SIP trunk.
4.4.3.2 Using G.729 as the codec on the SIP trunk
UC500
Model
Bandwidth
per call
MOH
port
Voice
(G729)
T.38
Fax
Transcoding HW
Conferencing
8/16 User
(PVDM2-32)
24 Kbps
1
8/16
4
6
2 sessions (16
conferees)
24/32/48 User
(PVDM2-64)
24 Kbps
1
24/32/48 8
10
2 sessions (16
conferees)
NOTE: All values listed are the maximum for each function – you must mix & match to
get the optimum # of calls that can be supported over the SIP trunk.
If there is a need by the SP to only use G.729 then below is the CLI you would need to
enter the below in config mode:
voice class codec 1
no codec preference 1 g711ulaw
no codec preference 2 g729r8
codec preference 1 g729r8
sip-ua
g729-annexb override
Also, transcoding is required in this case especially when going to voicemail (Cisco
Unity Express) as that only supports G711ulaw. A sample transcoding configuration on
UC500 can be done as shown below:
a. Find the MAC address to be used for transcoder:
UC500#sh int vlan 100 | inc bia
Hardware is EtherSVI, address is 001b.8fa8.4282 (bia 001b.8fa8.4282)
b. Configure the DSPs for transcoding:
voice-card 0
dsp services dspfarm
c. Disable SCCP services (affects only analog ports)
no sccp ccm group 1
Removing this CCM group will result the associated profiles (SCCP appl services) to
unregister with the active CCM or to bring down those appl services.
Do you want to continue...[y/n]? [no]:
y
no sccp ccm 10.1.1.1 identifier 1
sccp ccm 10.1.1.1 identifier 1 version 4.1
d. Re enable SCCP services and add transcoder MAC address from above. Note
the number of sessions is 6 in this case. This can change based on requirements
for calls and also is based on any other features that use DSPs being turned on or
off:
sccp ccm group 1
associate ccm 1 priority 1
associate profile 2 register mtp001b8fa84282