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DSP Calculation help needed for ISR G2 / PVDM3 using 10 concurrent ILBC calls

Has anyone heard when Cisco will be updating their DSP calculator to include routers with PVDM3s (

Until then, could anyone help me out to determine the number of DSP channels I'll need for the following, assuming I am using PVDM3 modules.

2921 VGW at main site, currently has a PVDM3-32

  •      1 ISDN PRI, 24 channels
  •      2 MTP sessions already configured
  •      2 conferencing sessions still need to be configured, but I'm out of DSPs.  (I'm not sure how many DSP channels each conf session reserves).
  •      10 concurrent voice calls using ILBC, a High-Complexity codec, needs to be accounted for, I'm not sure how many DSP channels each ILBC XCODE session reserves).
    •           We are using ILBC because our client has chosen to use site-to-site VPN over the Internet for inter-office calls, and of course we can't guarantee QoS on the Internet.

Currently the VGW has a PVDM3-32, I am able to configure two XCODE and two MTP sessions, but 0 conferencing sessions.

How many more DSP channels do I need to accomodate the list I mentioned above, in short, two more hardware conferencing sessions and 10 concurrent ILBC calls.



Re: DSP Calculation help needed for ISR G2 / PVDM3 using 10 conc

Give this is a shot.  This is the newest one available - supports selection of ISR G2 and then model.

You can also access it here: --> Just look for DSP calculator, it will take you to the link above.


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New Member

Re: DSP Calculation help needed for ISR G2 / PVDM3 using 10 conc

Top marks for you David!