Phone Status if Fiber Cut or Damaged

[armond_in_nj1]

I am investigating cellular backup for home security if the FiOS Digital Voice line is accidentally or intentionally damaged.  Specifically, if the fiber is cut outside the dwelling, does the ONT still maintain the 48 VDC across the inside phone lines (using either house 120 AC or the battery backup)?  The point of this question is that the cellular backup only operates when it detects no voltage over the house phone line.

[tns]

Interesting question.  Like to hear someone who actually knows.

My guess is it does keep the power going.  Note that you can identify your cell phone as getting calls when your FDV connection is not working.

[MDmo]

My security system doesn't depend on the home phone line at all, it automatically calls the monitoring company if there is an emergency problem using its built in cellular system.  That actually appealed to me and it's also not dependent upon the household electric system - It has its own battery back-up.

[armond_in_nj1]

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@MDmo wrote:

My security system  ... automatically calls the monitoring company if there is an emergency problem using its ... cellular system.  ... and it's also not dependent upon the household electric system ... 

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Good suggestion.  Using cellular as primary is getting more and more popular in the security industry as folks switch to mobile without a land line.  The unit I'm considering (Uplink 4550) can be programmed either way and is versatile in that respect.  However I do my own security and automation systems and the current FiOS DV line I use is very convenient for home automation, system control, and a few other things.  I'll probably keep it for at least some time.  BTW did you do your own system?  .

[armond_in_nj1]

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@tns wrote:

 ... you can identify your cell phone as getting calls when your FDV connection is not working.

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Yes, that is so, but of course in security applications, it's the outgoing call that is at issue.  The device I'm referring to in this case is purpose-built for security use and transmits security-related information and status reports in a very specific format (e.g., CID) to dedicated stations.  To be activated as a secondary calling device, it must be tripped by a problem in the primary line.  I'm not sure that's possible with VZ DV, since the applied line voltage is generated internally (by the ONT) rather than by the carrier.

[armond_in_nj1 · Accepted solution]

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@armond_in_nj wrote:

 ... if the fiber is cut outside the dwelling, does the ONT still maintain the 48 VDC across the inside phone lines ... The point of this question is that the cellular backup only operates when it detects no voltage ...

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After corresponding with the device manufacturer, it has been determined that the Uplink (and similar cell devices) will not capture the FiOS DV line if it is damaged or cut.  Since the 48 DCV remains across the phone line, the device is not activated.