The customer has 8 lines, 5 lines are programmed to ring in the store (answered separately) and 3 lines are programmed to ring in the back office. The back office telephones only give a one ring (like a notification) on incoming calls and flash after the initial ring. The customer says the problem comes and goes.
Any help would be appreciated.

That was never a feature on the Executech system, so something is definitely wrong. We will need to know exactly which KSU is installed, since all Comdial systems during that era were called Executech. There are about 12 different models. There is a label on the right side beneath where the power cord enters with an American Flag on it. If you can get us the numbers on the labels, we can point you in the right direction.

I really think that this might be more of a CO line issue causing ring trip on the back office lines. Those KSU's are pretty tough and when they fail, it's 100%.

Another cause for this is when telco call forwarding is activated and forgotten. A single reminder ring is sent from the CO and heard on the phones, but nobody is there on the line. Could this be the case? Maybe someone is forwarding the lines and forgetting to take it off? Either of these situations would cause the phones to ring once, then continue with lamp flash until the incoming call timer expires. That would also explain the inconsistency with the problem.

By the way, welcome aboard!

Welcome telephony121!

Ed, I completely agree that this may simply be an instance where call forwarding is assigned/activated in the telco for the 3 rear office lines. When CF is activated, the "single ring" is also a standard option in the 5ESS, we call it BSR (base station ring) default = Y, used as a courtesy reminder to the user that call forwarding is activated.

But, it would only happen on line one. Call Forwarding breaks hunting. If it's all three lines CF is not the answer.
Mark

Thank you gentlemen for the responses, but I dont think its the the call forwarding variable from the C.O. The incoming caller is still on the line buttons when answered.
I am unsure of the ksu model (I will confirm), but I did notice no grounding on any of the system components. That could create some pretty erratic behavior over time...couldn't it?

Thanks again.

telephony121,
You definately want to make sure that all components are properly grounded. Are the 3 back office phones assigned in a hunt group? Is the "single-ring" occurring on each phone "individually", per each phone's incoming calls?

"The incoming caller is still on the line buttons when answered."

I'm not sure I completely understand "when answered"...I presumed that after hearing the "single-ring", the customer was losing the incoming call (either by CF or disconnect).

Can you explain this in further detail for us?

Try bumping up the volume control on each phone.

How many stations or telephones are on the back 3 lines?

The old exec's only had off, low, & high. When they are off you don't get an alert signal like the new digitals. I would doubt that grounding would only effect 3 lines and a few phones but grounding is important.

I'd connect a single line phone to the line at the interface and see if it behaves the same way when the office phones fail, this will determine if it's your equipment or if you should be looking ahead of the equipment toward the Telco.
Mark

You can also try placing a test call to one of the back office lines (when the customer reports the "single ring" occuring) to observe the call treatment.

We recently had a customer reporting a similar problem; we quickly determined that they had unknowingly misprogrammed their forwarding, sending all their calls out to Scott AFB, Illinios.

5Etek-mike
Meaning the caller is not forwarded out of the telephone system via the variable on the central office line. The caller remains on the flashing line button until the button is pressed (all 3 lines).

STS E
There are 3 stations that are experiencing the problem.

Excellent. Thank you for clarifying.

It's just with this type of problem, we need the most precise information.

Please reconfirm our understanding of exactly what's occuring >>> During the times that the "single-ring" problem is occuring on the 3 back office phones: During an incoming call, the customer receives only a "single-ring", however the line button continues flashing. Once the flashing button is pressed, the incoming call cannot be answered.

Is this precisely what's happening?

He said it can still be answerred when the flashing line button is pressed.
What system are we talking abuot here?
Heck, even a phone model # would give us a bit more to go on. The KSU model number is probably a letter followed by 4 numbers, like N0616 or something similar, although it could be somethng like E60-PT as well.

Presuming all is right with the CO, you may have these sets programmed for call forwarding. The XE and older series could not forward but the E40,60,80 series could do a call forward. Try canceling the feature.
A station will give one ring burst if it's forwarded.

I am starting to like the idea of simply unplugging one of the line cords from the KSU and plugging it directly into a 2500 set. It's important to do it this way to rule out any issues with the lines and cords. If the phone keeps ringing on an incoming call, then it pretty much points at the KSU ports being bad. If the 2500 set also only rings once, then it's definitely a telco issue. This most simplistic form of testing might be the fastest and most reliable means of troubleshooting the problem.

You might also want to check for any surge protectors on these lines and bypass them during testing. Defective ones or ones that are rated for voltages too low will clamp down on the ringing current while still allowing talk battery to flow.

I was thinking the same thing, CF to a station or a voicemail that no longer exists.
Maybe someone put it into night mode (I think that the "E" series had that feature...)?

I looked it up to double check and the E series has night service.
Pending further info, and because you say it comes and goes, my guess is you have an "E" series KSU (Executech 2000) and someone is putting it into night service by accident.

The Comdial is a GO816 Rev I with a GM408 RevB expansion module. The telephones are 7714S-FB telsets.
Thanks everyone for all of your help thus far.

Sorry for the mix-up as far as ksu type. There is no voicemail on the before mentioned telephone system.

Thanks,
Telephony121

Huge difference from any Executech sytem. You have a DSU.
Someone has a night service button programmed on their phone and is putting the system into and out of night service.

That sounds like a Digitech system. Still, I don't know of any feature that system has that would cause this to happen due to a feature activation. I am still leaning toward an issue with the lines or a failure of the CO line ports. Are these lines residing on the expansion module or the base cabinet?

Since it is a DSU (Impact or Digitech), I would go back to it being ringer volume, unless that's already been ruled out. That could easily explain the intermittent behavior, and the single ring burst and subsequent flashing and ability to still answer.

That's right Justin. I believe there is a program setting that will stop people from being able to turn the ringer off isn't there. Called "allow ringer off" maybe?

I don't know where you get executech out of digitech. This must be why tech support always first asks "is it plugged in?"

Well, the old Digitech phones looked like the Executech phones, so that's somewhat understandable if you didn't look at the "Digitech" label on the face of the phone.

The allow ringer off was for either ring burst or nothing at all on the first ring. I wish it would make the ring burst option just be a muted ring instead. When I set Allow Ringer Off to no, I usually mean it.