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BE4K - PVDM Requriement



We just tried installing a BE4K with a T1/E1 Card. However, keeps throwing an error . TAC states that an additional PVDM Card is required for the T1/E1 card in addition to the on board PVDM. 


TAC reply - 

BE4K ships with PVDM4-64 on motherboard and must remain on the motherboard. You need a total of 2 PVDM4 modules.  One goes on the motherboard and one goes on the NIM T1/E1 card.  Won't be able to configure without both.


Can someone confirm this or am I missing something. 




Hi @harikeshan


It's correct. Same thing for cisco routeur series 4000.

The optional BE4000 Digital Multiflex Trunk (MFT) modules require the appropriate Cisco Packet Voice Digital Signal Processor Module 4 (PVDM4). For more information on the E1/T1 PVDM4 and configuration requirements, see


Data sheet here:




Best regards
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I checked the BE4K datasheet which says

The optional BE4000 Digital Multiflex Trunk (MFT) modules listed in the table require the appropriate Cisco Packet Voice Digital Signal Processor Module 4 (PVDM4).


You can check the table in Datasheet under Ordering Information.





Chris Deren
Hall of Fame Master

Aman is correct (+5), see the following note in the link he provided:


There is only one PVDM slot on the motherboard. The Time Division Multiplexing (TDM) cards can not use the motherboard PVDMs. Dependent upon the number of channels required, the appropriate DSP module is installed on the NIM. For IP services such as to transcode and conference, the PVDM4 DSP module can be installed on the motherboard of the ISR 4000 Series platform.

Hi @harikeshan


@Chris Deren is correct +5

@Aman Soi is correct +5

I was not so far...

Just check the different post with the data sheets proposal.

Best regards
******* If This Helps, Please Rate *******

Thank you All for your valuable inputs. Hopefully, this would be the last such oversight.


Quick question...

We are currently on ISDN with PVDMs on the NIM slot.

We are migrating our voice to SIP Trunk. Can I use the existing PVDMs on the NIM or do I need to purchase/reinstall the PVDMs on the motherboard for SIP Voice?

We need it for transcoding and conference service.




Suggest you to move it to motherboard if NIM won't be used anymore.

Nipun Singh Raghav
"We cannot solve our problems with the same thinking we used when we created them"

Few things to consider:

1. SIP trunk calls for the most part do not require DSPs as they are voip to voip calls, with that being said depending on your call flows, region configuration and applications used it is a good idea to allocate some transcoders for when they are needed, plus you can also use them for hardware conferencing.

2. PVDMs from NIM can be used as as media resources just fine, so as long as you remove your PRI configuration you can release the PVDMs to be configured. You can if you want to move the module to the single PVDM4 slot on the motherboard and remove the NIM.

For future reference the PVDMs from NIM can be used for media resources, but not the other way around, i.e. you cannot use motherboard PVMDs for NIM PRIs.

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