Use FXO ports instead of BRI ports

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Oct 11th, 2008
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Newbie to UC500 but experienced IP engineer: My model of UC500 has built-in BRI ports. I have purchased a VWIC2-2FXO card to use for the public switched network instead of the BRI ports. Cisco Configuration Assistant -> Configure -> Telephony -> Voice ->Device initially shows Built In: 4 FXS and Built In: 4 FXO. It then has a think about it and changes to Built In: 4 FXS and Built In: 2 BRI which is fine. However, it is only then that the panel below shows Public Switched Telephone Network and gives me the option of Basic Rate Interface BRI Switch Type. I can change this from the default Basic-NET3 to None but was hoping to see the FXO ports appear in the panel. Any assistance on FXO on VIC to be confogured for Public Switched Telephone Network would be appreciated. I have trawled various manuals but no joy so far.

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Rajesh Revuru Sat, 10/11/2008 - 19:12
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I wonder if it has anything to do with DSP count. But we will wait for someone to give some insight on that.

emrivera01 Sat, 10/11/2008 - 19:22
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If i run show hardware or sh inventory, the card does not show up either.

Rajesh Revuru Sat, 10/11/2008 - 19:26
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you may want to post the show inventory or show hardware here, so that we can see what kind of dsp resources it has

emrivera01 Sat, 10/11/2008 - 19:29
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Cisco UC520-16U-2BRI-K9 (MPC8358) processor (revision 0x202) with 249856K/12288K bytes of memory.

Processor board ID FHK113513YC

MPC8358 CPU Rev: Part Number 0x804A, Revision ID 0x20

22 User Licenses

10 FastEthernet interfaces

2 ISDN Basic Rate interfaces

2 terminal lines

4 Voice FXS interfaces

1 Voice MoH interface

1 cisco service engine(s)

128K bytes of non-volatile configuration memory.

125440K bytes of ATA CompactFlash (Read/Write)

UC520#sh inventory

NAME: "UC520-16U-2BRI-K9 Chassis", DESCR: "UC520-16U-2BRI-K9 Chassis"

PID: UC520-16U-2BRI-K9 , VID: V01

Rajesh Revuru Sat, 10/11/2008 - 20:02
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I am not 100% sure, but it has to do something with licensing. You are using UC520-16U-2BRI-K9, which means it only recognizes BRI. Probably you have to upgrade to include FXO ports in it.

See from the following


16-user Cisco Unified CME Base, Cisco Unity Express and phone feature license, 2 BRI ports, 4 FXS ports, and 1 VIC slot

More at the following URL

emrivera01 Sat, 10/11/2008 - 20:04
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I thought the 1 VIC slot would allow me to use an FXO card.

Rajesh Revuru Sat, 10/11/2008 - 20:14
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I guess the reason being the following. It either supports BRI or FXO with the amount of DSP resources.

. Does the Unified 500 Series have DSP limitations?

A. Yes. Each Unified 500 Series SKU comes equipped with a default DSP configuration and is not upgradeable in the field. Both 8- and 16-user SKUs comes equipped with two (2) 5510 DSPs. The 32- and 48-user SKUs both come equipped with four (4) 5510 DSP configurations


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