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New Member

Looking to add more BRI Lines


I'm looking to upgrade a Cisco 2921 system to add additional BRI lines.

The base system is a C2921-CME-SRST/K9 bundel (that has a PVDM3-32)

The existing HWIC slots contain two VIC2-2BRI-NT/TE modules, and one VIC3-4FXS/DID module.

(That's two 2-port BRI modules, and one 4port voice/fax module)

Currently, there are 3 BRI lines coming in, and 2nd port on second module is shutdown (according to cisco specs).

What should I be looking at if we want to add 3 more lines and incorporate conferencing? (as there are issues with conferencing now - possibly due to DSP availability?)

Can we add more modules? Should we replace the 2 port BRI modules with 4 port ones? Do we need to add more PVDMs?

Thanks in advance.

New Member

Looking to add more BRI Lines

Also would consider new system if necessary

VIP Super Bronze

Looking to add more BRI Lines

To my knowledge there is not a four-port voice capable BRI card, only the VIC-2BRI-NT/TE. You can certainly add one more of those as it sounds like only three of the four EHWIC slots have been consumed. The higher-density option would be a PRI instead of a BRI which would use a VWIC3-1MFT-T1/E1 card. Alternatively you may want to consider a SIP trunk which eliminates the legacy TDM handoff entirely and uses a software feature called Cisco Unified Border Element (CUBE) on the 2921 instead.

Any time you add additional voice interfaces, or want to increase dspfarm capacity you need PVDM3 capacity. There is a excellent calculator to guide you in the sizing process:

Please remember to rate helpful responses and identify helpful or correct answers.

Re: Looking to add more BRI Lines

Beware the four port BRI modules (HWIC-4B-S/T) as they only support data and not voice.

There is a module which may be of use at the URL below:

The basic module (EVM-HD-8FXS/DID) provides 8 FXS/DID ports and it can accomodate two expansion cards. There is a four port BRI expansion module available (EM-4BRI-NT/TE) so this card could potentially give you 8 x FXS/DID and 8 x ISDN BRI.

It was originally designed for the 2800 routers and needs an adapter (SM-NM-ADPTR) for use in the 2900 series. It is also old so may be due an End of Sale notice soon.

The card does not provide any DSP resources so you may need to add extra PVDM3 resources to your 2900.

As mentioned by Jonathan I would have a think before commiting to lots of BRI circuits. PRI or SIP is likely to be more cost effective in the longer term.

New Member

Re: Looking to add more BRI Lines

Thanks guys.

Just 2 more questions:

1. Would we be fine to take out the VIC3-4FXS/DID module and add 2 VIC2-2BRI-NT/TE modules?

2. How can I tell if more RAM would be needed to support the additional modules?

Re: Looking to add more BRI Lines

1. Yes this should be fine (config checked using the Cisco Build & Price Tool)

2. The default memory should be fine for this.

You need to think about PVDM's though. With the PVDM3-32 already installed you would be ok for 16 voice calls using low or medium density codecs.

If you want to use high complexity codecs or features like transcoding, conferencing, MTP etc. you would need to add more.

Use the link that Jonathan posted to learn more.

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