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Problem with DSP profiles on 3845 router

Hi guys ,i have a 3845 router ,and when i configure the dsp profile for conferencing it gives me a maximum sessions option of 0 only ,so i am unable to unshut the profile and get the conference bridge registered in CUCM. The router is running c3845-adventerprisek9-mz.124-22.T.bin ,any ideas ?


Re: Problem with DSP profiles on 3845 router

This could be attributed to the lack DSPs, especially if you are using high or flex codec complexity?

Can you confirm what codecs you have enabled within your profile? If you remove G.729 and only allow for G.711 are you then able to configure max sessions?

If this is the case, then there are insufficient DSP/PVDMs installed in the gateway.

Could you post a 'show inv'?

Remember that each timeslot on voice modules will automatically be allocated a channel, and are not a shared resource.

Hope this helps.


Re: Problem with DSP profiles on 3845 router

You don't have enough DSPs. Conferencing is one of the things that when you set it up on the router, it takes the DSPs immediately and reserves them only for conferencing. This is different than for a PRI that uses channels as-needed. As well, conferencing requires a full DSP.

Use the DSP calculator to figure out how many you need:



New Member

Re: Problem with DSP profiles on 3845 router

Thanks guys ,problem is now resolved ,i had only one PVDMII-64 installed which would have been enough for the 1 PRI and the conferencing ,but i had configured both PRI ports and this consumed all the DSP`s ,so i just removed the config from the second PRI interface.

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