Trunk to trunk transfer problems.

[Foxtele]

Legend R6. 14 POTS lines. 8 DID (copper) trunks.
Site complains that the caller and recipient of the transfer get a loud "squeel" after the trunk to trunk transfer is completed. TESTED all pots trunks, with no problems.

Problem occurs whencall comes in on ANY DID trunk and you transfer off premise. As soon as users hit transfer the 2nd time, you get a squeel kinda like holding a microphone in front of a speaker. Talked with SBC for 4 hours and they say once the call is terminated at our switch, their responsibility is over.

This worked fine until a few months ago and just stopped.
SBC's tech support says that they cannot guaranty signals/voltage for a DID line piggy backing on to another pots line.

NEED HELP. I am at a loss and dont trust SBC.

 

[merlinman]

What we have here is probably an IMPEDENCE MISMATCH.

It sounds like some of your trunks are "TOO HOT", transmission wise.

Fixing this would require "BUILDING OUT" these trunks with RESISTORS to make them look (ELECTRICALLY) like they are LONGER than they really are.

I could provide a SCHEMATIC on how to do this if you email me.

 

[comdata]

Hi Merlin, what is your email address, I'd would like to get a copy of that schematic. Thanks for the info.

Alex

 

[merlinman]

m e r l i n m a n AT c o m c a s t DOT n e t

Take out spaces and substitute the right things and it'll get here.....

 

[aussie88]

I would not be surprised if it did have something to do with SBC, I cant stand them. They were doing some "regular maintenance" up at the CO, which managed to send a major surge through the line, that managed to get through the surge protector, and into my 1030 (I loved that thing) control unit, Kablooie.

Best of Luck,
A G

 

[SYQUEST]

Hi Foxtele,
Which SBC end office is the Legend served from? You can have unintended consequences sometimes when changes are made to outside plant. For instance, loaded verses non-loaded cable, pair-gain or remote carrier terminal where it used to be miles of copper, or CO changes where they added VF loop repeaters to improve levels and transmission. But the telco does NOT always inform the customer about these types of changes!

If you access to a TIMMS and know the local milliwatt number, you can measure the level loss or gain of each line.
Just curious do the lines squeal when you do a trunk-to-trunk with 2 of the dialtone lines (not DID)?

Hope this helps!

....JIM....

 

[merlinman]

Yes, that would be a good test as well....

 

[Foxtele]

No, All pots lines are fine if I do the transfer with both POTS. The squeel is only when a DID is involved.

 

[Pepperz]

DID's are to "hot". They can be "turned" down by the CO.

Pepperz@charter.net

 

[SYQUEST]

Hi Foxtele,
The same conditions apply to DID trunks on copper as pots, except in the CO they terminate on channel units in a channel bank. It could be someone changed the settings or the CUs by mistake, hence the hot levels. Open a trouble ticket w/ SBC and request that the levels be measured at the MPOE. They will need to send a "tech" to the prem to do this.

I have had this sort of thing happen before w/ Pacific Bell. They had the wrong channel bank, a nite person was setting one up for an order due the following day and could not count!

BTW, which SBC end office is the Legend served from?

....JIM....

 

[Furball8675309]

As i understand, the tech was going there with a berry box. Would that do the appropriate test?

 

[SYQUEST]

The Berry Box does not measure transmission levels. It can monitor trunk
signalling and audio, decode DTMF or MF, and do trunk termination and signalling functions, but for levels you need a transmission measuring set or TIMMS. HP (Agilent) and HALCYON (now CXR Telcom) make such equipment.

The Berry Box can be a lifesaver! I have used one over the years to solve DID problems for both analog and digital situations, especially dealing with Pacific Bell. That along with my Halcyon 701A are two of the best investments for test equipment I have made in the past.

Hope this helps!

....JIM....