Question on MGCP IOS transcoder and Software CFB

Hello All,

I am using my BR1 router as a MGCP GW. I have configured IOS based
transcoder on this MGCP GW and successfully registered to CUCM. I am using software
based conference bridge on the CUCM which is in a different
Devicepool/Region. Between Regions G729 codec is negotiated. In this
case when I try conferencing 2 BR1 phones with a PSTN call, the BR1 Phone initiated the conference is hearing a busy tone and other BR1 phone gets connected solely to the PSTN.


Once I moved the software based conference bridge on the CUCM to BR1 device pool everything is working fine.

I
tried to replicate the same with H323 GW and I do not find the above
mentioned issue. I am suspecting if we can use IOS based transcoder on
MGCP GW and Software based Conference bridge on CUCM which are different
Devicepool/Region.

Please let me know if my understanding is wrong. Please find below my configuration.


BR1-RTR#sh inventory | inc PVDM
NAME: "PVDM3 DSP DIMM with 16 Channels on Slot 0 SubSlot 4", DESCR: "PVDM3 DSP DIMM with 16 Channels"

PID: PVDM3-16          , VID: V01 ,


!


controller T1 0/0/0

 pri-group timeslots 1-3,24 service mgcp


!


dspfarm profile 1 transcode 

 codec g729r8
 codec g711ulaw
 codec g711alaw
 codec g729ar8
 codec g729abr8
 maximum sessions 4
 associate application SCCP


!


sccp local Loopback0

sccp ccm X.X.X.X identifier 2 version 7.0
sccp ccm X.X.X.X identifier 1 version 7.0
sccp
sccp ccm group 1
 associate ccm 1 priority 1
 associate ccm 2 priority 2
 associate profile 1 register IOS-XCODE-BR1

!

voice-card 0
 dsp services dspfarm

Comments

  • Well, CUCM software based conferencing uses only G711 codec.

    If you have inter-region G729 , then you will have to use transcoder.

    Once you move back devices to the same pool it has started working, since everywhere was G711.

    It is not dependant on gateway signalling protocol that is in use. 

    Why it didn't work with MGCP, probably could be transcoding errors.

    You will have to look at CUCM traces to see why xcoder didn't allocate for that call.

    But as a best practice use G711 codec relation between regions where CUCM SW Conference resides and phones.

     

     

  • Hi Nizami,

    yes, you are right. First, I forgot the basic that CFB supports only g711, secondly, my transcoder assigned maximum of 2 sessions, so when CFB in different Region, 2 BR1 Phones uses the 2 sessions of transcoder to speak to CFB and when I tried to conference a PSTN line, the phone initiated the conference is thrown out. PSTN phone and other BR1 phone gets connected to each other directly instead of using a CFB. Once I made my transcoder sessions to 3 or more, everything
    is fine.

    I forgot the basics which made me think weird about the technology :(.
     
    Thanks & Regards,
    Vignesh S


    On Friday, 10 January 2014 10:58 AM, nizami <[email protected]> wrote:
    Well, CUCM software based conferencing uses only G711 codec.

    If you have inter-region G729 , then you will have to use transcoder.

    Once you move back devices to the same pool it has started working, since everywhere was G711.

    It is not dependant on gateway signalling protocol that is in use. 

    Why it didn't work with MGCP, probably could be transcoding errors.

    You will have to look at CUCM traces to see why xcoder didn't allocate for that call.

    But as a best practice use G711 codec relation between regions where CUCM SW Conference resides and phones.

     

     



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