sundance-communications.com/forum Forums TDM Business Telephone Systems Avaya - Lucent Telephones & Systems Definity s8500 analog ring cadence

Hi,

We are installing a modem bank for a customer who has a Definity s8500 running version 13 software.

Due to the odd ring cadence emitted by the PBX, the modems refuse to recognize the ring as valid, and thus won't answer.

Without measuring, I would estimate that the internal ring is approximately 500-700ms on, and about 4500ms off. An external ring is about 250ms on/off/on and again about 4500ms off.

The owner's PBX admin, and their vendor say they don't have any way of changing the timing to be more compliant with the North-American standard of 2sec on, 4 sec off.

Changing the modems isn't an option.

So the question is, are the settings either in a class-of-service, or on a global/localization level that would alter the ring cadence and allow both internal and external calls to present with a traditional ring cadence?

Thanks,

This may have to due with running modems over IP. 'disp ip-codec x' page 2 where x is the codec that you are running for that network region 'disp ip-network-r x'. On page 2 of the codec form, make sure that modem is set to "relay" or "pass-through", try both to see what works. I have seen many time where it is set to "off" and modems and faxes just wont work.

My question was whether the ring cadence on analog stations can be changed, either on a per-station, class-of-service, or global level.

With the odd ring cadence, the modems are not convinced that the phone is ringing and thus won't answer.

If we can get to a point where the modems will reliably answer, then I suspect we'd be concerned with audio quality through the PBX.

As it is, the inbound traffic will be from local ISDN-PRI trunks and terminate to analog stations in the same node.

Is this modem bank something like a Brook trout card connected directly to their PRI?

Modem Mode Specifies the mode for modem calls. Valid values are:
● off
Turn off special modem handling when using this codec
set. In this case, the modem transmission is treated like an
ordinary voice call. This is the default for new installations
and upgrades to Communication Manager R2.1.
With a codec set that uses G.711, this setting is required to
send modem calls to non-Avaya systems.
● relay
For users in regions using this codec, use relay mode for
modem transmissions over IP network facilities.
● pass-through
For users in regions using this codec, use pass-through
mode for modem transmissions over IP network facilities.

No. These are analog, loop start, modems connected to analog (i.e. 2500 phone set) station ports.

The problem is that the analog ring cadence (i.e the periodically presented, 90VAC 20Hz signal) has a non-standard ring cadence, which the modem's software refuses to recognize as a valid alerting signal.

In my original post, I provided the rough timing values of what I currently see. Said differently, the internal call ring is a short single ring, and an external call is a quick double ring.

I want to know if the PBX programming can be changed such that the analog station's ring signal, for both internal and external calls, is 2 seconds ON, and 4 seconds OFF.

Google had turned up some Avaya documentation for what must be a newer PBX, because that documentation clearly indicated that the "Ring Type" for 3 or 4 different call types could be changed on a per-station basis, and that "RingType4" was 2sec on, 4sec off. HOWEVER.... the PBX Admin indicated that they don't see anything like that in their programming options, and the local vendor says that it "can't be done" with this PBX.

Though I have a strong telcom background, and experience on a variety of manufacturers equipment, I do not have experience with this particular PBX, nor am I responsible for it's care and feeding. For this job, I'm having to work through individuals which have very little understanding of telephony.

Again, to be clear, all I'm currently interested in is with a Definity s8500 running version 13 software, can an analog stations ring cadence be changed to 2 seconds on, 4 seconds off?

IF so, how?

Thanks,

Liquidvw...

I appreciate what your responses are conveying, and I know that some PBX's have problems with providing an undistorted audio path for a modem.

That said, IF we can get to a point where the PBX will generate a north American ring cadence, which in turn will cause the modem's in this group to actually answer, THEN we could begin to analyze how well the modems will work.

When the ports were initially setup, they were not defined for modem use, and when I forced one of these modems to answer and establish a connection, I was only getting connect speeds of 1200bps.

Since that time, the PBX admin had redefined the ports as 'modem'. I've not been back on site to see what if any affect this had on the modem's ability to negotiate a higher speed.

In this particular setup, the customer has four geographically disparate locations, each with its own PBX/node, and all networked together. The site with the modem's has ISDN-PRI trunks locally available, and all calls of interest will be received via these trunks. I would hope that this represents a best case scenario for call quality between trunk and station. From what I saw, the analog station ports we are using are in a different bay (not sure what the correct Lucent/Avaya term is), than the PRI trunks.

Until we find a way to change the ring cadence that the PBX is generating, discussion about call path settings is a bit academic.... especially if we have to contract with a LEC for loops and bypass the customer's rather significant PBX investment.

Thanks,

The modem will never work until you change your codec.

That does NOTHING! chaning the set type to modem is not a change that will fix anything. "modem" is not an avaya supported set type. It's an alias of the 2500. 'disp alias station'.

I'm not sure why your not willing or able to make a simple codec change.

Never say never. If the called modem decides to answer (elaboration below), or if I manually force it to answer an inbound call, then indeed I can establish a reliable data connection.

There are a couple of ways that I can get the called modem to answer. The first is to issue a command to it, while the PBX is ringing that station, to cause it to go off hook and generate answer tones.

The other way I can sometimes get it to answer is that of the analog station's in this group, one of the PBX ports appears to have slightly different ring timing and will more often than not satisfy the modem's ring validation logic... and this is only on the internal call cadence. I didn't have a scope with me during initial installation to measure the timing difference, but I imagine that it is slight. The external call cadence never satisfies the modem's ring validation logic.

... and no, these modems don't support the AT-SDR (distinctive ring) feature.

Ok, thank you for that additional information.

I believe I have disclosed that I came here for help because I'm not intimately familiar with this product line. Additionally I am forced to work through an admin that handles moves/adds/changes, and anything much beyond that involves their vendor.
It was not my intent to convey an unwillingness to make a codec change. I have simply been trying to get my original question answered.

As to the question of ability, access to the site involves a minimum of two hours of travel time to validate any changes we make. The customer also incurs support charges when faced with something that their admin can't handle in-house.

If my original request has a solution, then we'd request the owner, or their vendor, to implement all the recommended changes.

Their vendor has said that "it can't be done". My 20 odd years of telcom related experience causes me to question that answer, but if the collective/authoritative knowledge here is that "it can't be done", then I'll remove that possibility from our rather short list of options.

Given that the modem's firmware doesn't interpret the PBX's ring cadence as a valid ringing event, until that issue is addressed, anything beyond that is somewhat academic.


My options at this point, which do not include using different modems, are:

1.) Ascertain information on how to reprogram the PBX to generate a standard north American ring cadence.

2.) Ask the modem manufacturer to modify their firmware to accept the PBX's non-standard ring cadence. To that end, I'm working that as a parallel effort, but it may not be the most expedient solution.

3.) Contract with a LEC to provide local loops and remove the PBX from the equation. This of course results in higher recurring costs for the customer.

4.) Install a ring stretcher between the PBX and modems.

I trust that my more complete response sufficiently explains the situation, and why I keep steering the conversation back to my original question.

Thanks,

Dude your killing me. Your tring to reinvent the wheel. Just dial in via the RMATS port, no travel required. 'cha ip-codec x' and set the modem to relay or pass-through. Then test the modem. I bet it works.