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Community Member

Power fail phones in Cisco enviroment

Hi,

How can we have analogue phones connecteced to Cico IP analogue gateways operate in a in a power fail scenario like standard legacy PBX feature.

CCO says the following

FXO Power Failover During power failure to the router, this feature enables a direct metallic path between an FXO port and a special "red" telephone to provide a direct line to the PSTN.

Is there any documentation on how to get this working setup and how it operates with analogue phones?

9 REPLIES
Hall of Fame Super Red

Re: Power fail phones in Cisco enviroment

Hi Ravi,

Here is some info including cable pinouts, for how these are setup;

The FXO expansion module supports a power failure port that connects directly to the central office (CO) in case of failure.To maintain an emergency connection during power outages, connect port 14(Expansion module 0) or port 24 (Expansion module 1) to the public switched telephone network (PSTN). Phones connected to port 8 or port 18 fail over to the PSTN connections through port 14 or port 24 during power outages.

From this good doc;

http://www.cisco.com/en/US/products/hw/modules/ps2797/products_installation_guide_chapter09186a008007c8ce.html#wp1022948

Q. What is FXO Power Failover?

A. The FXO Power Failure feature is a hardware feature built into the FXO cards that allows connectivity to an analog phone patched into the right pair of wires to be activated by a relay if power to the Cisco router containing the NM-HDA fails. This allows PSTN calls to be made via the FXO line normally connected to the router from a designated "red" phone in the office while power is out. For an FXO EM in slot 0 of the NM-HDA, the analog phone must be connected to wire-pair 14 (counting from 1 on the RJ-21 connector) to take advantage of the FXO Power Failover feature. For an FXO EM in slot 1 of the NM-HDA, the analog phone must be connected to wire-pair 24 (counting from 1 on the RJ-21 connector) to take advantage of the FXO Power Failover feature. If both EMs are populated with FXO modules, two "red" phones can be used.

From this Q&A doc;

http://www.cisco.com/en/US/products/hw/modules/ps2797/products_qanda_item0900aecd8017014a.shtml

Hope this helps!

Rob

Please remember to rate helpful posts.....

Community Member

Re: Power fail phones in Cisco enviroment

Thank you

Community Member

Re: Power fail phones in Cisco enviroment

Rob,

I realise that this is an old post, however I am having problems getting an answer to my query with NM-HDA Red Phone deployment.

My requirement is for PSTN exchange line to utilize an FXO Port on an NM-HDA module. This FXO Port shall trigger a Hunt Pilot Point on Call Manager. In the event of a Router power failure the PSTN exchange line shall then ring an anaolgue phone.

Do you know If this can be achieved?

thanks

Ian.

Hall of Fame Super Red

Re: Power fail phones in Cisco enviroment

HiIan,

No worries my friend!

I'm not positive about the "FXO Port shall trigger a Hunt Pilot Point" part of the config, but I don't see why this couldn't be manipulated somehow. The Power Fail portion of the config will certainly be achievable. The PSTN FXO line is wired through a set of contacts on the NM module that will engage in case of a power outage. The cct. can be wired directly to the Red Phones via in house wiring.

Hope this helps!

Rob

Community Member

Re: Power fail phones in Cisco enviroment

Rob,

Thanks for the feedback.

The documentation is somewhat unclear stating that Port 14 should connect to the PSTN and analogue phones connected to port 8 failover to the PSTN through port 14 during power failure.

If this is true then the PSTN exchange line sits idle until Router power failure.

Ideally we would like to utilize the PSTN exchange line, which shall be MGCP controlled with failover during power outages.

Is the documentation incorrect?

Ian.

Hall of Fame Super Red

Re: Power fail phones in Cisco enviroment

Hi Ian,

Isn't this documentation always tricky :)

The FXO line can be used for both Powered and Power Fail scenarios. The cct. connected to Port 8 will switch to Pair 14 (connected to Red phone) during power fail and the cct. connected to Port 18 will switch to Pair 24 (connected to Red phone) during power fail.

"Tip: To maintain an emergency connection during power outages, connect port 14 or port 24 to the public switched telephone network (PSTN). Phones connected to port 8 or port 18 fail over to the PSTN connections through port 14 or port 24 during power outages."

http://www.cisco.com/en/US/docs/routers/access/interfaces/nm/hardware/installation/guide/connhda.html#wp1022948

Hope this helps!

Rob

Community Member

Re: Power fail phones in Cisco enviroment

We have had issue with the 25 pr fxo/fxs module. we have went to the hd2ve modules. The easiest way we do power fail is reconnect outside lines to the leftover voice outlets after the installation. Line one and two sits by the switchboard operator. and several lines throughout the building. We have "Power Fail" phones stored in the Data room to plug in during emergencys

Community Member

Power fail phones in Cisco enviroment

Hi,

Does anyone know if the power failue feature is supported on VIC2-2FXO interface?

Thanks

Bryan

Gold

Power fail phones in Cisco enviroment

Hi Bryan

No, as far as I know, it isn't. I believe it is only supported on the high density modules:

http://www.cisco.com/en/US/docs/routers/access/interfaces/nm/hardware/installation/guide/exvoimod.html#wp1076451

HTH. Barry

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