Incoming calls on pots line port not ringing through to the phone.
gary-gary:
This is an OBi110 configured as follows:
google-voice service on SP1
pots line hooked to line-in port
analog phone connected to phone port
using all default OBi settings
confirmed the Line Port InboundCallRoute = ph
I can make and receive calls via google-voice. I can also press # and make outgoing calls via the pots line. However incoming calls on the pots line do not ring the attached phone. The line LED on the OBi flashes during an incoming call, and if I monitor the 'Line Port Status', I see it indicates 'Ringing'.
I am trying to set this up for my parents, who have recently moved to an apartment in a retirement community. The pots line comes from the facility's PBX. I do not know the details of this other than the residents can call each other by simply dialing 4-digits, or can dial 9 to get an outside line followed by a 10-digit number. I believe the phone system is also part of an emergency notification system as each room is equipped with a pull cord & speaker to summon help.
The Line Port Status shows the On Hook 'TipRingVoltage' as -21V. I've also confirmed this with a multimeter. I've unplugged all the phones with no change to this. Is this possibly the issue?
I tried lowing the 'LineInUseVoltageThreshold' from the default 25V to 18V. The only effect was to get a single ring from the analog phone when the calling party hung-up.
Suggestions? I am remote from this unit, so while I can access it via the OBiTalk website, I can not easily make physical changes or measurements.
-gary
ianobi:
Quote
The Line Port Status shows the On Hook 'TipRingVoltage' as -21V.
This could well be the issue. A standard POTS PSTN line would measure around -48v. Looks like the local PBX there is a low voltage system. This means it may well put out low voltage ringing current. Try a lower setting here:
Physical Interfaces > LINE Port > Ring Detection > Ring Threshold
Quote
I tried lowing the 'LineInUseVoltageThreshold' from the default 25V to 18V.
This setting tells the OBi if a parallel device is in use. If another phone is off-hook, then the line voltage drops and OBi knows not to barge-in. It's hard to say what it should be on that system without measuring. Of course, it does not matter if there are no parallel devices.
gary-gary:
Quote from: ianobi on August 03, 2013, 09:54:38 am
Quote
The Line Port Status shows the On Hook 'TipRingVoltage' as -21V.
This could well be the issue. A standard POTS PSTN line would measure around -48v. Looks like the local PBX there is a low voltage system. This means it may well put out low voltage ringing current. Try a lower setting here:
Physical Interfaces > LINE Port > Ring Detection > Ring Threshold
Thanks for the response.
Do some PBXs actually use such a low voltage? I'm still not sure if this is a PBX issue or an OBi one.
I had considered changing the 'RingThreshold' parameter, but my measurements of the ringing voltage (both by meter & OBi reporting) seemed to indicate that there was plenty to meet the ring threshold. I'll try a lower setting when I can get my parents to reattach the incoming phone line.
The PBX had no trouble ringing their regular phones, including a couple of old 500 series phones with the mechanical ringers (as can the OBi!).
The OBi110 was flashing the line LED & reporting 'Ringing' in the following menu:
Status > PHONE & LINE Status > Line Port Status > State => Ringing
Yet it did not send the call from the POTS line to the phone. ???
-gary
ianobi:
A public Telco type telephone exchange may have to ring four phones on the end of a ten mile copper line. It has to put out around 90v a.c. and plenty of current. A PBX is designed for an office building or similar, so it can put out a lot less current at a lower voltage. The a.c. ringing voltage needs to be measured with a load on it - a phone or two or in this case with OBi connected.
Quote
Status > PHONE & LINE Status > Line Port Status > State => Ringing
This raises an interesting point. The PHONE & LINE Status seems to simply report what is there regardless of configured setting. If the ringing voltage was below the threshold it would still report it as being there. We have many examples of CallerID appearing in the same Status section, but not being processed by the OBi.
Quote
residents can call each other by simply dialing 4-digits, or can dial 9 to get an outside line followed by a 10-digit number.
After you solve the ringing problem, you may wish to come back for a better digit map. There should be no need to press # to get the POTS line. OBi could route calls automatically with the correct digit maps.
gary-gary:
OK, I got my parents to temporarily re-cable the unit and I made the changes remotely to the following menu:
Physical Interfaces > LINE Port > Ring Detection > Ring Threshold
I changed this from the default setting of 40.50-49.50
to 19.35-23.65, and then
to 13.50-16.50
There was no operational change... i.e. the attached phone still does not ring when a call comes in on the POTS line port. :-(
-gary
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