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Forum Index : Microcontroller and PC projects : I need an autodialer...

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Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 3423
Posted: 06:41am 12 Apr 2021
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Correct me if I am wrong, but I understand that in essence the problem lies within the VOIP system that does not have a UPS (or at lease not the whole system).

Tell the IT guys to fix that, in stead of finding workarounds, and don't take the argument for hearted that the whole system is too much power for a UPS. Complete google datacentres have a UPS. There are plenty of bigger ones around, the bigger ones are mostly hybrids (battery/flywheel for the first minute, then a diesel generator kicks in).
There should be plenty of arguments to fix this, what about humans wanting to call for help (even as simple as the front desk) when there is a power outage.

Volhout
Edited 2021-04-12 16:43 by Volhout
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Mixtel90

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Joined: 05/10/2019
Location: United Kingdom
Posts: 5648
Posted: 07:20am 12 Apr 2021
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I'm rather surprised that a UPS on any phone system that may be needed to make emergency calls isn't mandatory. In the UK exchanges have supply batteries and either their own standby generator or somewhere to connect a mobile one so that the chargers can carry on running. VOIP systems are the responsibility of their owners, but the broadband link will be on the exchange battery supply.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9030
Posted: 10:00am 12 Apr 2021
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@ Volhout: I hear you.  But I.T. guys quoted thousands and thousands of dollars to UPS backup the entire system, as it is quite big and spread out over a very large area, and even if they did that, it would only hold the system up for 10-15 minutes(their words).  No office phones will work in a power cut, including reception.  The management are aware of that.  It is odd though, cos even the old PABX had battery backup and all the extensions would work in a power cut.  But they say this is progress......

@ Mixtel90: It IS mandatory, which is why we can't feed it via the new network VoIP system, as it is not battery backed up.  This is EXACTLY why I am looking for another solution.    I expect UK's regulations regarding emergency phones on doors or in lifts is pretty much the same thing as here in NZ.  MUST be battery backed and MUST work if there is a power cut.  

EDIT: Correct spelling of Volhout's username.
Edited 2021-04-12 20:02 by Grogster
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robert.rozee
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Joined: 31/12/2012
Location: New Zealand
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Posted: 10:24am 12 Apr 2021
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so what you have at the moment is a speaker/microphone and a single 'call' switch in the elevator? pressing the 'call' switch connects the device to the phone line, and then it WAS the responsibility of the PABX to then dial out in response?

essentially, like a normal wired phone, but without any keypad? the 'call' switch goes from on-hook to off-hook (how does the person in the elevator hang up?).


that being the case, it seems that what you are after is something that detects the line voltage dropping to less that 15v or so, and in response injecting a sequence of DTMF tones down the line. it seems to me that these tones could be recorded on an MP3 player module, with the output spliced into the microphone circuit.

is this right?


cheers,
rob   :-)
 
ryanm
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Joined: 25/09/2015
Location: Australia
Posts: 191
Posted: 10:26am 12 Apr 2021
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Haven't read the whole thread so someone might have mentioned this. Those new IP phones have a setting to autodial on reciever pickup (probably, don't know the brand or model) Let me know if you want more details.

I have this set up on my desk phone, it autodials my mobile if you don't press a key after 3 seconds.
 
Grogster

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Posted: 10:42am 12 Apr 2021
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@ Rob: Yes, you have it EXACTLY right.  That is it precisely.  I was thinking along the lines of a MM chip and a DTMF encoder wired to the line, but I simply don't have the time to develop and test a setup like that, as they need it fixed ASAP for the building WOF.  If I had a little more time.....    The elevator phones and door-phones are on a call-duration timer.  Push the button, the line is connected, you can talk for up to five minutes I think it is.  The PABX would terminate the call, when the staff member hangs up their end of the call, then the lift phone switches off after the timeout period ready for the next time.

@ ryanm: Yep, they probably do, but we are not using VoIP phones on the doors or lifts - they are plain old analog speakerphones, basically, with only one button.  Nice idea if it was a phone in a hallway or something, and I have seen setups like that at taxi-stands for example - pick up the phone handset, and it will autodial the taxi place, and you can order a taxi - that kind of thing.  But we have no handset to speak of here, just a button.

A member here did email me a company in Aussie(NatComm) and they DO have a little box of tricks that will do exactly what I want(Model DS9 Dial Out Telephone Line Controller) for A$300, so I do have a path I could go down in that direction if push came to shove.
Smoke makes things work. When the smoke gets out, it stops!
 
robert.rozee
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Posted: 11:12am 12 Apr 2021
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presuming that internet access comes into the building over fibre... would it be practical to battery-back JUST the ONT and device providing PPPoE?

in my own home network, i have the standard huawei ONT bolted to the wall as provided by chorus, that runs off 12v DC. this feeds into an edgerouter lite (also running on 12v DC) that has TWO downstream gigabit ethernet ports. one port connects into a 16-port switch that then services the rest of my network, the other port is spare and can be livened up to provide an independent outside connection.

if your building has internet coming in to the building in  similar way, then a VERY small USP would be able to back up ONT + PPPoE device + a PAP2T which would then provide an autodialling FXS/POTS pair to run off to the emergency phones.


even IF internet for the building is not handled in the above way, it may well be easier (and in the long-term cheaper) to swap out the existing POTS line for a dedicated fibre connection, and then shell out for a UPS + ONT (free?) + edgerouter lite (or similar) + PAP2T.

a fibre connection is around $65/month. i'm picking a POTS connection is a tad more these days.


in fact, my ONT already has two FXS/POTS outlets, but they are not livened up and are under control of chorus. it may be worth giving them a call. the HG659b modem spark gave me for free also has a couple of FXS ports. this gives a couple of other routes to the same ends, but may require a little more trickery to get autodial. a PAP2T, on the other hand, is a known working solution.


cheers,
rob   :-)


addendum, manual for PAP2T:
https://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/csbpvga/pap2t/administration/guide/pap2t_user.pdf
Edited 2021-04-12 21:14 by robert.rozee
 
CaptainBoing

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Joined: 07/09/2016
Location: United Kingdom
Posts: 1983
Posted: 12:48pm 12 Apr 2021
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  Mixtel90 said  I'm rather surprised that a UPS on any phone system that may be needed to make emergency calls isn't mandatory. In the UK exchanges have supply batteries and either their own standby generator or somewhere to connect a mobile one so that the chargers can carry on running. VOIP systems are the responsibility of their owners, but the broadband link will be on the exchange battery supply.


you are definitely on the right track, even to the point I think it was the Telecommunication Act 1949 placed a legal onus on the PO to correctly alert "subscribers" when a call was waiting - i.e. ring the bell. Early portable systems using huge 4-pole 1/2" plug/sockets would have a slave bell that rang when the phone was unplugged to ensure the PO wasn't in breach. When PST phones became the norm and everyone could unplug the phone ("opting out of service") the jack socket even had a CR circuit to simulate the bell circuit of the phone so an external text could prove the connection was all the way to the socket by looking for the "kick" on an ohmmeter as the capacitor (1uF?) charged through the resistor (470k?). odd where we started. The capacitor is needed to AC couple ringing current to the ringer pin, but the resistor serves no purpose other than enabling visibility of the ringer circuit to a meter at the exchange (or anywhere along the line actually).
 
Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 3423
Posted: 01:05pm 12 Apr 2021
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Hi Grogster,

I respect your effort to find a solution that is cheap and practical, especially under such pressure. And I know New Zealand is not the US, UK or Europe, where regulations simply cannot be taken lightly.
I am just scared that if something happens as result of humans not being able to communicate, that it backfires on you. They always look for a culprit... You knew of the risk, and you implemented a workaround...

And what is a few 1000 dollar UPS and a Honda generator (15 minutes give you plenty of time to start it manually) in exchange for a human life ?

Please be careful !

Regards,

Volhout
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Mixtel90

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Joined: 05/10/2019
Location: United Kingdom
Posts: 5648
Posted: 03:46pm 12 Apr 2021
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VOIP has been around for some time and so have lifts. This will have been solved already by someone. I'm surprised the suppliers of the VOIP gear can't come up with something.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
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