VG204(SCCP) and OTIS Remote Elevator Monitoring (REM) Problems

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Jun 21st, 2010
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I have a customer that has OTIS Elevators using the REM (Remote Elevator Monitoring) system. (Not just an Analog Connection) The way that I have been told that it works is that when a user pushes the "Help" button, the Elevator then starts a Data Connection sending the various errors codes. It will then swap into a voice connection after the data has been pushed. This swap point is where I have the problem. The connection appears to just drop when they attempt to change modes. Apparently this works fine on a normal Analog connection, but the VG204 does not understand what it is trying to do.

Does anyone have any experience with this Elevator type, and what might need to be added to the port parameters to make this work? I talked to the manufacturer and all they could tell me was that it is proprietary and that it works all over the world, but they recommend a normal Analog Connection from the Telco Provider. As this is not to helpful, I am hoping someone might have experience with this Elevator type before I open a case.

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Jonathan Schulenberg Mon, 06/21/2010 - 09:21
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First, I will echo the manufacturer in recommending a straight analog loop. I say this because you do not want to be on the hook for making sure the elevator phone works in an emergency such as an extended power outage. How long does your UPS run for all of the equipment involved (UCM, switches, VG204, and PSTN gateway)? What happens if something such as a data center fire triggers an emergency power off (EPO)? The emergency systems such as alarm panels and elevator phones need to keep working. I make a point of keeping them off of the VoIP infrastructure.

Having said that, the VG204 is likely switching to modem relay mode. To my knowledge a call cannot revert to voice after the DSPs initiate relay mode. You can try disabling modem/fax relay (pass-through only) and seeing how this works. This will make the connection extremely susceptible to errors though. Even small amounts of jitter or delay can cause modem calls in pass-through to fail. Make sure that things such as VAD are disabled and the call always uses G.711.

Keith Fulcher Mon, 06/21/2010 - 09:47
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Thanks for the prompt answer. I follow your logic with the seperate lines for emergency devices, but the customer wants to take the risk. I have passthrough setup already, so that is not the fix. I attached the config and CUCM settings so that you may glance through them. I am open to any suggestions, because this one is a hard one. If it works on a plain old analog line, then it should work on the VG204. Something is just missing....

kle000002 Sat, 12/06/2014 - 09:02
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Sorry to warm up this old old thread, - it seems to be the only factual source regarding this special OTIS REM / VoIP matter.

The proposed solution here to use a legacy PSTN line for OTIS REM system is comprehensible, - though not really cost-effective. Well, the main problem is to get now (in 2014) a PSTN line! In Central Europe the local and regional Telcos are switching consequently to VoIP. They want to terminate their analog legacy PSTN networks in the near future. So the PSTN option is / may no longer avaiable.

My idea was originally to try a most recent PoE based VoIP to PSTN adapter, like VIP-156PE from manufacturer Planet. After a request, their Tech Team discouraged me strongly to use it in this emergency call related situation. No compatibility could be granted, - only normal analog to SIP VoIP connections are supported. Well, as Jonathan Schulenberg said, - no VoIP to PSTN adapter seems to be designed to handle this special behavior of OTIS REM system.

In consequence, it seems that there exist no other solution then GPRS / GSM mobile phone connection option for OTIS REM. So, was this really definitely so?

No! It seems that there exist at least one other possibility. According to the information I found, most DOCSIS / PacketCable based cable modems should be able to handle this special operation of OTIS REM. For example, Cisco's (Scientific-Atlanta) DPC/EPC2203 cable modem series support at its RJ-11 ports explicitly also analog modem connections. It seems that the way how cable modems are converting PSTN to digital is more reliable / considerably then normal VoIP to PSTN adapters.

At the moment I cannot confirm that it works, - will see it in February / March 2015 when the new OTIS lift (including OTIS REM) will be installed.

If this really works, you only have to worry about an UPS which powers up the cable modem and TV cable amplifier for some hours. That should be feasible I think.

MICHAEL CARTER Fri, 03/30/2012 - 06:08
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Hello Keith,

I am stuck with a very similar problem with my customer in Denmark regarding these elevator alarm phones.  Did you get a solution to it in the end?  I'd really appreciate some pointers as I'm also experiencing the providers and manufacturers brick-wall of "it's standard and works everywhere else" answer.


Keith Fulcher Tue, 04/03/2012 - 02:38
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Never got it working... not even with the Cisco TAC. The customer decided to get dedicated provider lines for these cases.


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