Direct inward dial problems merlin legend

[charliehummel]

We have been experiencing DID problems on a Merlin Legend System. They Are normally caused by severe thunderstorm activity during the summertime. My question is two fold.

What can we do to prevent Card damage to Merlin Legend cards due to induce voltage from lightning.Induced on telco lines, not on power lines. We have multiple buidings connected via underground and above ground pairs Thru conduit to the PBX location.The plant facility is over 100 acres. We are also working with a pretty limited budget which has forced us to bring the maintenance function in house on the system.

What is the proper methodolgy of problem isolation (EI: is it a Telco problem,, or is it a Card problem on a DID circuit.What DID circuit is the root cause of the problem

A little general theroy on the conection methodogy on DID circuits would also be appreciated.

The problem on the DID circuits shows up when the CO responds with a "Im sorry please try again later" msg to the telephone trying to reach one of the DID stations at our location.

By the way Ill solve your AS400 problems if you solve my Telco problems. I am not a Telco expert

Thsnks

 

[ken07734]

Any feeds between buildings should be terminated to lightining protection, the co lines and external lines, DID, etc... should placed on some type of sneak protection. All systems should be properly grounded via the grounding screws on the power supply's. All systems should be on UPS's capable of holding power for about an hour as well as regulating the power in the event of a surge.

 

[bobsou]

if your DID is allways saying after i"m sorry its the telco who has busy out your trunks , if you were replacing your circuit packs ,then the surge is coming your way even surge protector have problems with lightining ,but offer some protection, its sounds like the telco is protecting their CO

 

[charliehummel]

A little further info. Because of a business reorganization the merlin legend replaced a definity system which did not seem to be as sensitive to lightning problems. As far as I can tell the ins and out to the system are protected by little black sq plug in units, which I assume are the line surge protectors. The Co lines are additionally protected by some sort of transparent fuze used as a bridging clip on the 66 blocks. I will agree with a potential equipment ground problem. I have asked that the maintenace personel to validate the grounds on the equipment and the line surge protectors assumming that the black sq plug in units need a path to ground in able to protect the lines correctly.

I would still like to know the correct method of diagnosing a fail did line

thanks
charlie

 

[bobsou]

if we are talking DID Trunks,their ground start go to your d'marc place a butt end telephone, across your trunks ,dial your DID station if it works your good ,the problem is then the telco, you may also have reversed pair,which one of their teks,change somewwer in their outside plant ,happens here all the time ,but according to telco we didn't do anything

 

[franke]

Actually, a DID is a 'dry' pair between the switch and the Central Office. The switch (Merlin) supplies -48V & Ground to this pair therefore it is imperative that the correct polarity be observed. If power is lost to the Merlin, the C.O. will sense the loss and busy out the affected trunk or trunks. In most cases, the C.O. will automatically restore the trunks once power is restored, though if they have been out a reletively long period of time it may become necessary to call the provider and have them 'release' the trunks.

As bobsou staes, the typical method of testing a DID trunk is to connect a butt set to the trunk and dial (rotary or TT, depending on programming) an extension number. When you go off-hook at the D-mark, you should also 'hear' the wink (a clunking sound)if the trunks are programmed for wink start. If you do not 'hear' the wink than the port is probably locked up and you may have to reset or replace the module.

franke

 

[Ghostin]

If these are analog DID trunks, make sure your have lightning protection as Ken stated. If is is coming in via a T-1 connection, make sure you have a CSU installed. It will help some of the over voltage problems. Make sure your switch is properly grounded as well. Technically, IROB surge protection should be used on all MLX sets that are in remote buildings, however, standard lightning protection circuits seem to work better in most cases.

 

[charliehummel]

Thanks for the info everybody. A few further questions on DIDs

I did use the butt set and do hear the wink on most of the circuits. After the "wink" what digits should i dial on the butt set the last 3 ei: the station number, all seven numbers. XXX-yyyy or the last four . Hitting the DID with the correct digits combo,, should this make the station ring? Should I remove the bridging clips to the co before I do this ? Do I need to use a ground to indicate to the switch I want the pair ? By the way one DID returns no wink, another DID is returning a repetive wink. I busyed out both of the DIDs at the switch so now I am left with 5 that appear to be good.

At the CO does the C.O. step thru the DID.s looking for an available circuit, or does it use a procedure similiar to a C.O. Hunt group just step to what it thinks is the next available DID.

I really appreciate the answers I am receiving

Charlie

 

[TouchToneTommy]

If you have a butt set with polarity LEDs, such as a TS-22, when you go off hook you should see them go Green/Red/Green showing the wink. Do this with the bridge clips between you and the CO removed. Make sure your clips are connected observing the polarity of the CO side. A Legend expects you to terminate the DID trunks on a jack, and use a standard telephone line cord (which crosses over polarity) to connect to the Legend. If you are using a cable with a modular on one end, and punching the other end down to the telco block, you must reverse polarity at your side of the telco block. This is true for DIDs and Ground Start trunks.

Are your trunks programmed for Wink start or Loop Start?

The number of digits for you to dial will be found if you print out the DID trunk report in SPM. The telco is sending some certain number of digits, that in some way match your extension dialing plan, and the Legend can strip off digits and add digits to make it match.

The CO will step through the DID trunks with each call, even if the previously used trunk is idle.

Any recordings being heard by the caller are generated by the telco.

Sometimes a certain trunk will be out of service due to a telco problem. Monitor the trunks with your butt set while you call in with your cell phone, and you will hear the CO seize the trunk, the wink signals, and the digits coming from the CO. Test each trunk and make sure that are all OK.

 

[SYQUEST]

Hi charliehummel,

There is a thread #689-481100 from FEB03 titled "What does DID interdigit timeout mean?" that covers this subject matter. It may be helpful to you in troubleshooting your DID problem.

....JIM....