PBX Disconnect Problem

Posts: 3 · New Forum Member Joined: Nov 15, 2004 Posts: 3

I posted a reply elsewhere regarding this, but wanted to see if someone might have an idea. I have an Inter-tel Axxent PBX and a couple of the RT31P2's. Calls that aren't picked up by an extension stay latched after the caller hangs up.

Vonage says this is a known problem with some PBX's and they don't guarantee compatibility with a PBX. They said the router sends a disconnect notice. I'm not sure what it sends. It could be tone based. After the hang, the call routes to the operator and I can grab it. When doing so I hear a slow busy followed by a fast busy and then silence.

I've connected an ammeter and the current never changes when the caller hangs up. I would expect either reverse current or an open in the loop. In any case, the PBX doesn't appear to have anything to detect.

Bottom line, calls stay latched for several minutes and finally go to the voice mail, tieing up the line all the while. Any ideas? Thanks in advance. Brett

Posts: 1 · New Forum Member Joined: Nov 19, 2004 Posts: 1

The problem you are having is that by default the Linksys adapters do not send a CPC disconnect signal.

CPC, as you seem to understand since you tested for it, is a reduction of voltage to less than 1 volt for a specified duration after the remote party hangs up. It can also be a polarity reversal instead. The US standard is a 200ms voltage drop. The reason for the signal is to notify hold buttons and PBX's that the remote party has hung up.

On the Linksys boxes, that are of course actually Sipura boxes, the default settings for CPC are a 2 second delay and a 0 second duration. It's that 0 second duration that is causing your problem.

This can be changed, but only by Vonage on the Linksys box since you are locked out of the admin functions. The problem is that no one you talk to is going to have a clue what you are talking about, so you will need to be very specific and very persistent.

First of all, you might avoid using the term "PBX" since that does give the tech support person a good reason not to help as they don't support PBX's. I would suggest that you explain that the hold buttons on your phones will keep the line off-hook after the remote party disconnects. That, by the way, is a true statement so long as you have phones with hold buttons. Smile

Next explain that you absolutely know how to fix this. Tell them that there is a parameter in the Linksys called "CPC Duration". Tell them you would like them to set this to .2 (that's a decimal then "2" for 2 10th's of a second or 200ms). With that level of specificity, anyone at tech support should be able to do it for you. I would also ask them to note what they did in your account and that it solved your problem so that when you add more adapters in the future, you can just have the next tech read the notes.

I've done this on 3 linksys adpaters successfully so you should have no problem. By the way, I did use the "PBX" word and it was almost a deal killer at the start. Fortunately I was having issues with hold buttons at another location, I knew exactly what the problem was and how to fix it, and I got a very helpful tech who was willing to read the articles I pointed him to so he did the deed. Once he had the notes in the account, getting the next ones done was a breeze.

Good luck!

Posts: 3 · New Forum Member Joined: Nov 15, 2004 Posts: 3

Thanks. Worked like a charm. I was sure there was a setting, but the techs won't talk about settings. In the interim, I have a Call Progress Detector chip on the way and was going to program a PIC to open the line when a busy is detected - and it only took 45 min of hold time!

Have a great day. Brett

Posts: 1 · New Forum Member Joined: Dec 29, 2004 Posts: 1

Thanks for the setting. Was hard to make it changed by Vonage rep. I used the linksys router with a Nortel system, works better set to 1 second of CPC duration.

Vonage should enable it by default !

Posts: 1 · Posted: Fri Feb 11, 2005 10:09 am Post subject:

Excellent post - worked very well with knowledgable rep.
Thanks

Posts: 7

Great post. I have a dialogic based Televantage PBX and other IVR and CTI applications at customers. I was about to run my tone learning program and set up a disconnect tone for all the tones that go on for 4 minutes after a call hangs since I could not get into the voice part of the box. I had the rep set the CPC duration to .5 and works great. Lot easier and works much better than analyzing a disconnect tone after every call. Works like a real loop start line now. I don't know why they do not set this up by default, I am sure it messes up a lot of people's equipment.

Jay
CTI/VOIP Application Developer & Consultant

Posts: 244 · Posted: Fri Mar 11, 2005 6:17 pm Post subject:

wow, I dont have any setup or problems but this was some great info.

Dconnor, this may be something good for a sticky.

Posts: 7

I agree AspectTec that this thread should be kept as a sticky.

Many people are not familiar with the VOIP boxes and Vonage does not let you change or look at the voice stuff so people may be wasting their time or money (buying a box that does loop current reversal) trying to fix this simple problem. It also messes up fax/modem routing boxes and a lot of diferent phones.

I have worked with a lot of old PBXs that did not give LCR and we had to disconnect based on the disconnect tone. I could not find any specific information on the Lnksys RT31P2-VD so did not know what was inside it and this thread was very helpful, the tech did not know what I was talking about but did it.

I am not yet familiar with the Aspect phone hardware, but should be soon, too bad I can't use dialogic boards with it, have a bunch of them here.

Jay
CTI/VOIP Application Developer & Consultant
support@ITC1990.com

Posts: 244 · Posted: Fri Mar 11, 2005 8:19 pm Post subject:

The Aspect hardware is all proprietary unfortunately and Im not prone to recommend their stuff much anymore since we use alot of I3 Software now with Dialogic/Aculab boards.

One thing I can say is that the Aspect is very easy for me to program and integrate CTI solutions with and the system is VERY and I mean VERY reliable running for more than a year at times without a reboot and thats on a windows platform! Thats an accomplishment in and of itself.

Most of the modern PBX/ACD systems we use that are windows based like a monthly reboot it seems.

btw Jay, I buy any hardware I need from Specialized Resources in Texas (They resell/refurb used stuff) and are about 60% cheaper than Aspect is.

I have a contact if you need anything.

Posts: 67 · Posted: Sat Mar 12, 2005 10:54 pm Post subject:

PetDude wrote:

The problem you are having is that by default the Linksys adapters do not send a CPC disconnect signal.

Tell them you would like them to set this to .2 (that's a decimal then "2" for 2 10th's of a second or 200ms).

Would this solve the answering machine problem where it continues to record a slow busy and then fast busy until it times out?

??