Land Line for Intercom (without local phone service)

Started by wolf2011, April 10, 2011, 04:05:06 PM

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I have an OBi110 unit set up with GV. The only part I couldn't get it to work is the land line to the intercom in my apartment building when I try to open the gate for visitors.

I do not have local phone service, but the intercom system works correctly when I connect the phone directly to the phone jack. When the phone is connected thru OBi110 unit, the land line to intercom does not work as expected. The phone rings when someone dials my apartment unit, but the signal gets cut off as soon as I answer the phone.

Any suggestion? Thanks for helping me out.

Update: After changing the trunk group 1 as primaryline for phone and AA, the phone does not ring when dialing thru the intercom system.


Trunk Group is for outbound calling.  If you only intend to make calls through Google Voice, PrimaryLine should be left at SP1 Service.

The OBi has several methods of detecting LINE Port disconnects and operating parameters.  You'll find them at:

Physical Interfaces -> Line Port -> PSTN Disconnect Detection


Physical Interfaces -> Line Port -> Port Settings

You'll probably have to experiment with these settings, disabling and/or adjusting them to see if you can determine which one(s) are causing the OBi to hang up.  A multimeter to measure the line voltage and loop current would probably also be helpful.

Most likely, you're in uncharted waters with your gate control/intercom.


When I was playing around getting both my Obi's to interact with each other it seems I remember that the Obi doesn't connect to the Line Port unless it detects service on the line.

pressing **8 or # gave either,  "there is no call route available" or "there is no service available".

Once you pick up the phone after the ring, the Obi detects a dead line and cuts it off.


Is there a way to set it so that it will connect without detecting service, short of somehow injecting voltage on the line?


The gate control/intercom is likely trying to emulate a telephone line, supplying battery and ring voltage, but it may be terribly outside the normal specifications an OBi is used to seeing.  For all we know, it may be sending CPC, Polarity Reversal, or a Disconnect Tone right at the beginning in case it's an answering machine that picked up.  Without doing a little detective work as well as some experimentation with OBi settings, it's all speculation.


If I had to guess, my bet would be that the gate equipment is sending low on-hook voltage, probably only 24 volts or less.  So go to the OBi110's web portal (NOT the OBiTALK portal, but rather the device's web browser - you may need to dial * * * 1 to get the IP address), then expand "Status" in the left-hand menu and go to "PHONE & LINE Status", and see what voltage the Line Port Status shows when the line is connected and the phone is disconnected (or on hook).  If it's less than 25 volts, that's the problem.  The LineInUseVoltageThreshold and LineInUseCurrentThreshold can be adjusted under the Physical Interfaces, Line Port settings (on either the device or by using the Expert mode of the OBiTALK portal - if you use the OBiTALK portal to configure your device then you will have to make the change there, or it won't "keep").
Inactive, no longer posting or responding to messages.  Goodbye and good luck.  Some of my old Obihai-related blog posts have been moved to - note this in NOT my blog; I have simply given the owner permission to repost some of my old stuff.


Thanks for the suggestions. I ended up buying a $10 analog phone to hook up with one of the phone jacks. It works out better this way, since the new phone gives me a different ring tone for calls from the intercom system.

Just want to say that you guys are great! Thanks for all the helps.