Home Phone stops working several times in 2 months

[JLU_LINY]

Hi, my mother's home phone loses connection 1x - 2x times a week.  All of a sudden, usually hours later the phones start working again and days later it start all over again.  A Verizon technician has been to the house 3x and on one occasion changed the Fios hardware.  The issue continues, they are never on-site when the system is out.   We are no better than the first time it happened

We only find out the phone line has gone out because when we call the home phone the call is redirected to her cell phone number and we get her cell voicemail.  We go to her home, chat with support, try unplugging the base phone from power and the RJ11 phone port, unplug all the secondary cordless phones from power, and plug back in starting from the base.  This doesn't work, and to eliminate the phones as being the source of the problem we swapped out her phones with our own and the issue continued to happen at her house.

There's only one phone number and two drops, one for the phone base and one for the alarm system.  

Speaking with my IT Director he showed me the Verizon Fios system at work.  I thought her phones are on a POTS line but he said it's digital now.  Somewhere the system must convert from digital to POTS in order to use the same phone and alarm devices in the home.  Can someone please explain it to me and how can I relay the ongoing issue properly to support/ Verizon technician to get this fixed once and for all?  Thanks.

[dexman]

Based upon the description of the problem, I'm wondering if it is being caused by the alarm system.

In situations where an alarm system shares a single telephone line with telephones, the wiring is done in such a way that the alarm panel is able to "barge in" to a telephone call that is in progress, dump the call, grab the now idle telephone line and call out to wherever. If someone tries to grab the telephone line when the alarm has control of it, it will appear to be a dead line. 

So if the line is dropping calls, or is "dead" when trying to place a call, it would point to the alarm system using the telephone line for one reason or another.

[JLU_LINY]

Thanks for your response.  I called the alarm company and spoke to the owner/installer.  He doesn't think it's the alarm based on what I told him.  I texted him to see if his central station records any history of the line down and the length of time it's out.  

My mother's ONT is different than mine.  Mine is older.  Her's now has a back box on the outside of the house (in the white Fios box attahed to the house), another black box inside the basement and then the wireless router in the main section of the house.  How is the phone line supposed to be set up now?  The last tech said he thinks he knows what's wrong and was supposed to talk to his peer sand return.  It's been over a month and no one's returned.

[dexman · Accepted solution]

The ONT at your mom's is on the outside of the house. It is inside of the white enclosure that was used with the old ONT.

The inside box would likely be the ONT's  power supply "brick".

The only way to know for sure how the telephone wiring is setup would be to physically trace it out starting from the outside ONT on in as far as possible.

If there was a problem with the ONT of the fiber optic feed, other services that she might have (cable TV and/or Internet) would crash at the same time as the telephone.

My hunch is still towards the alarm barging in, but that is just a guess on my part.