OBi110 and Intercom

[ianst]

Hi all,

I've made some progress with my intercom connectivity through the Obi but just need a bit of help understanding if what I want to do can be achieved!

The intercom handset I have has three connections into it (plus lock release)
2 of the connections are for 2 way audio and are 'always on'. You can always lift the handset and 'hear' the intercom at the other end.

When the intercom button is pressed, a modulated electronic tone of 12Vpp-0.25A  is sent across the third cable which sounds out through the handset earpiece whilst the button is being pressed.

I've successfully connected the 2 audio connections into the LINE port of the OBI which shows as on-hook and about 14v TipRingVoltage. I've left the third connection directly between the intercom and handset so pressing the buzzer 'rings' the handset.

Trouble is - I stumped now what to do next!
There's no 'ring' facility through the Obi since the audio is always on and the 'buzzer' cable goes around it - what I want to do is have the intercom button ring a SIP phone and get the Obi to connect to it.

Can anyone help??

Cheers

Ian

[ianst]

Slight update:

Had the LINE wires the wrong way round.
Swapped the wires over and the TipRingVoltage is now registering -13v with a solid green LINE LED.

Still stumped where to go next....

Cheers

Ian

[Shale]

1. The "intercom handset" is at the far end, and you have wired that to the Line jack? That sounds strange. I would have thought that the intercom would be like a phone, but I presume you are implying that the intercom supplies its own battery current.  Maybe you have a block diagram of your plan? I had thought of searching through your prior posts, but I thought it would be better if you provided the description.

Are you planning to make the Phone port unused?

2. This is the first that I had read about the polarity of the Line coming in to the OBi110 to be important.

[ianst]

Hi Shale,

Thanks for replying so quickly - I'll try and explain it a bit better!

This is an intercom system between a gate and the house which also has a remote gate unlock facility.
At the moment it's all temporarily rigged up in my home office (!) but when properly installed there will be a door station with keypad (buzzer button and microphone/speaker) by the gate. This is connected to a 240v transformer by the gate which supplies power to the door station/pin pad and onwards to the handset.
The handset will be in the house and is a simple device with a single button to activate the remote gate locks.

My plan was:

Door station by gates has CAT5e up the house which would normally be directly connected to the intercom handset.
I 'insert' the Obi110 between the door station and handset (door station on the LINE, handset on the PHONE) so that when someone presses the buzzer on the door station, the original handset on the PHONE port rings as well as various SIP devices (SIP handsets in the house plus SIP clients on iPhones etc).
I've got the LINE side and PHONE side connected, but struggling to get my head around the dialing side of it given the fact that the 'ringing' part is a third cable between the door station and handset and the audio channel is always open.

Diagram of the kit in the link:

http://avaccesscontrol.co.uk/datasheets/PRS240.pdf

Cheers

Ian

[QBZappy]

Google the following: (copy and paste the entire line)
site:http://www.obitalk.com/forum/ intercom

Lots of references here to what you are trying to accomplish. Maybe you can find a solution in one of these posts.

[ianst]

Hi QB,

Thanks for the response - I've tried googling every combination of intercom/buzzer/line wiring I can think of and still draw a blank....

The issue I've got is if the Obi can deal with a LINE connection that is permanently open but with a third wire for 'buzzer' - ring.

Ian

[Shale]

In your test rig, if you press # from the phone, can you talk back and forth?

[ianst]

Hi Shale,

Just tried with a regular phone connected to the PHONE port because the intercom handset doesn't have a keypad.
I get a dial tone, then press #, (the LINE port goes into off hook) then cannot hear anything then 2 seconds later it resets back to a dial tone and the LINE LED goes out and comes back on a few seconds later.

The Call history shows a connected call on LINE1 outbound then a disconnection after 2 seconds.
During that 2 seconds the call status shows both phone and line connected.

Ian

[ianobi]

Ian,

I fear I may be the bearer of bad news on this topic. Looking at the "home" phone – CT on the diagram, you have a four wire unbalanced telecom circuit – I'm ignoring the gate release for now.

Pin 1: microphone single wire paired with earth return.
Pin 2: receiver single wire paired with earth return.
Pin 3: Common earth or ground (terms depend on where you live!)
Pin 9: 12v a.c. "ringing" which returns via the receiver to earth.

Effectively, this means that the transmitted speech is using pins 1 and 3 as its audio pair and the received speech is using pins 2 and 3 as its audio pair. The ringing comes in on pin 9 and is disconnected when the handset is lifted.

The OBI is looking for a balanced pair for transmitting and receiving speech and receiving ringing. It might just about be able to cope with the low voltages (they are configurable to some extent), but not with the wiring configuration.

There are types of doorphone that can be made to work with an OBi110, but I don't think that this is one of them. Maybe this company makes some sort of interface unit with a PSTN line – that would work with an OBi110.

[ianst]

Hi Ianobi,

Thanks for your detailed response.
I suspected this might be the case  -
I must admit I hadn't researched enough the configuration of the Intercom system before getting it just assuming it would be based on a simple PSTN line system which is what left me confused by all the cables! Lesson learnt - must.do.more.research..
I've emailed the supplier in case they have any suggestions.

On the off chance anyone else can recommend a UK intercom system based on PSTN technology I would be very grateful.

Thanks again for all the fantastic support.

Ian

[QBZappy]

ianst,

If you plan on starting over, I would suggest that you try using the fewest incompatible technologies as possible. If you want to use the OBi, a "pure" sip end to end solution would make it easier to accomplish what you are trying to do. Read this thread for an idea of how it can be done. If you decide to use a sip enabled product like the Grandstream product suggested in this thread, you get the added benefit of being able to see who is at the door since it is a sip enabled camera with the ability to control an electric door strike.
   
"Buzzing" in by digit press, Intercom
http://www.obitalk.com/forum/index.php?topic=2666.0

[ianobi]

Ian,

Here's a slightly messy idea using some of the parts you already have!

Look at it the other way around. Replace the gate phone with a standard weatherproof / vandal resistant phone. Using one pair of the cat5e cable, link that phone to the OBi110 Phone Port.

The OBi Phone Port can be configured as a "hot line". When the gate phone is picked up the OBi can be configured to dial any number out of the PSTN Line Port and/or a sip phone or softphone etc. Direct calling to an ip address on the same subnet of your router is fairly easy.

You would have to keep the transformer / gate latch etc and just use simple push buttons to open the gate.

This depends on how you wish to use your OBi – you would be losing the Phone Port to the outside gate.

If a sip phone is involved it would need to be configurable to "call without registration".

Anyhow, I'm just throwing a few ideas into the mix. You could try it all out using a standard phone plugged into the Phone Port before committing to fitting a weatherproof phone on the gate.

[ianst]

Hi both  - thanks for the replies.

QB - that looks like a very good solution - I'll have to see how easily I can source it with a waterproof enclosure. Also I'd need to work out how people initially contact us to let us know they are there waiting! The gate is at the end of the drive which is about 100m long - not massive but long enough it's not always visible! Presumably a SIP call alert based on motion in a very specific area could do it? Mobile phone signal where we are is almost non existent so can't rely on that (plus some delivery drivers don't have mobiles)

IanObi - Great idea - just need to try and source a weatherproof phone for a reasonable price. Quick Google suggests 500 GBP! I've already got an Asterisk SIP server up and working on my LAN which the Obi/SIP handsets/iPhones are registered to.

Cheers

Ian

[QBZappy]

Presumably a SIP call alert based on motion in a very specific area could do it? Mobile phone signal where we are is almost non existent so can't rely on that (plus some delivery drivers don't have mobiles)

I wouldn't trust motion detection. In my experience it is not reliable. You could use a cheap buzzer to ring inside the house to notify you that someone is at the gate. The cam is equipped with internal speaker and mic and can be powered over the cat cable or with a wall wart. Connect it to your router using a network cable.

Good luck.

[ianst]

Thanks QB - looks like a great piece of kit.

I think I might have to change plan and go for a SIP end to end solution with a fully SIP compliant intercom device unless I can get a weatherproof PSTN handset as IanOBI suggests for the Obi110.

Our house isn't massive but it is big enough that I think a buzzer handset at one side probably won't be heard the other side, which is why I've started off down the SIP/OBI route! Plus also going the SIP route gives me far more flexibility for routing calls across the Internet.

We've got 5 DECT/SIP cordless phones placed around the house, plus 2 iPhones and iPad which are always nearby, which seemed to me to be the obvious choice for the gate intercom to 'patch' through to. It's getting the link in the middle that's proving difficulty without spending large amounts!

Thanks for all your suggestions so far - I'm sure I'll work out a reasonable solution eventually! 
The obvious answer is more than one regular intercom handset for coverage, but that's nowhere nearly geeky enough for me 

Cheers

Ian

[dircom]

If you want geek get this
http://www.amazon.com/dp/B00BCQ7H3O/ref=as_li_qf_sp_asin_til?tag=nerdvitt-20&camp=14573&creative=327641&linkCode=as1&creativeASIN=B00BCQ7H3O&adid=1KMFVH2CPRRQ15CRZ7WK&&ref-refURL=http%3A%2F%2Fnerdvittles.com%2F%3Fp%3D6443

[ianobi]

Here's a neat solution for £158 + VAT:

http://www.tlc-direct.co.uk/Products/DEBT901.html

It's designed to connect between an incoming PSTN line and the house phones – or OBi110 in your case.

Caller presses the button sends ringing towards your OBi Line Port. OBi rings Phone Port / sip phones / softphones etc. You answer, talk to caller. If you want to release the door lock simply dial "1". Looks like it will work from any phone in your house.

The manual is not well written, but seems quite straightforward. Your wiring will be much simpler than the diagram, as you don't seem to be involving a PSTN line.

We like a good story on this forum, so please let us know which way you solve the door entry problem. Of course, a story with a happy ending would be nice...   

[ianst]

Hi IanObi,

That is a brilliant solution - well done for tracking that down!
Ironically I've used the company over the last 8 months for lots of electrical wiring/light fittings/sockets/cat5e etc for our house renovations - should have paid more attention to all the sales catalogues they keep sending in the post! 

I'm going to give the manufacturers a call to see if they can add a keypad to the panel (looks like they can) then get one ordered - in my case I won't need anything connected to the PHONE port since all calls will be SIP.

My only concern is the recommended limit of 50m between the control box and entry device - my run is probably about 80m - guess there must be some margin for overun.

Cheers

Ian

[Lavarock7]

Also I'd need to work out how people initially contact us to let us know they are there waiting!

100' of 2-wire, a battery, a door bell and a door bell buzzer.

or

A wireless doorbell may be good enough.

Do you really need to talk with the people? I would think if they cared enough to "ring your bell" you would want to at least:

a) Go down and say "hi"
b) Tell the 60 Minutes film crew that you have 'no comment'
c) Go down and look surprised when the Publishers Clearinghouse van is parked there with a big check

(if not in the U.S., ignore #2 and #3 as they may not make any sense)

[Shale]

d) listen to a presentation for new siding and gutters
e) get a presentation on alternate utility suppliers
f) take a "survey" where question 3 is "do you have a cemetery plot?"
g) a pair of missionaries to convert you
h) politicians going door to door before the upcoming election
g) etc