Hardware Conferencing in SRST mode (CBarge)

In a scenario where a customer wants to enable Hardware conferencing while in SRST for CBarge as well as in normal operation. We can configure this by registering the conference bridge first to the Call managers and then to the telephony service IP source address. In this way when the gateway will go in SRST, its Conference bridge will register with telephony-service (CME) thus enabling the Conference Bridge for use.

voice-card 0
dsp services dspfarm


sccp local Loopback0
sccp ccm identifier 1 priority 1 version 6.0   << Primary Call manager
sccp ccm identifier 2 priority 2 version 6.0  << Secondary Call manager
sccp ccm identifier 3 priority 3 version 6.0 << Tertiary Call manager (CME – SRST)
sccp ccm group 1
bind interface Loopback0
associate ccm 1 priority 1
associate ccm 2 priority 2
associate ccm 3 priority 3
associate profile 1 register HQconf

dspfarm profile 1 conference
codec g729r8
maximum sessions 2
associate application SCCP
no shut
sdspfarm units 2
sdspfarm tag 1 HQconf
conference hardware
srst mode auto-provision none
srst ephone template 1
srst dn template 1
srst dn line-mode dual-octo
max-ephones 5
max-dn 10 preference 5
ip source-address port 2000
timeouts interdigit 5
time-zone 8
time-format 24
voicemail 15623402221
max-conferences 8 gain -6
moh music-on-hold.au
multicast moh port 16384 route
transfer-system full-consult
secondary-dialtone 9
create cnf-files version-stamp 7960 Jun 09 2010 15:00:49
ephone-dn-template  1
call-forward busy 15623402221
call-forward noan 15623402221 timeout 8
ephone-template  1
softkeys remote-in-use  CBarge Newcall
softkeys idle  Newcall Redial Cfwdall
ephone-dn  1  octo-line
number 3020 no-reg primary
conference ad-hoc
preference 5
no huntstop
ephone-dn  2  octo-line
number 3030 no-reg primary
conference ad-hoc
preference 1
no huntstop
ephone  1
privacy off
ephone  2
privacy off

We will have to force the ephones to have “privacy off” otherwise they will have it enabled by default as they fallback in SRST. If privacy is enabled, CBarge will not work. You can either use auto-prov none (preferred) or use auto-prov all and edit the ephone-dn.

Note: The above solution was prepared by me months back after trying different approaches. I just found that Cisco has released (August 2010) a bug CSCti11843 which explains that how this CBarge thing can only be achieved the way I have explained above. Bug description as follows:

CSCti11843 Bug Details:

Shared-line Cbarge remote-in-use softkeys not working in SRST

For Shared line if you want cbarge you must disable privacy and enable remote-in-use softkey under ephone-template. However if you configured SRST CME with srst mode auto-provision none or dn privacy setting on the ephone remains default which means it is on. Hence you can’t disable privacy.


When phones fallback to SRST.


Only workaround is to either configure:

ephone 1
privacy off

or configure srst mode auto-provision all


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