No Dial Tone On Trunk, But Calls Ring to the PBX 1

[LAdrummer]

Can someone help me understand what kind of CO trunk I am dealing with?

I am surveying a school's trunk lines (going to their phone system) and found a group of numbers that have no dial tone at the demarc. However, these trunks ring the phone system when I call them and I can hear them ring my test set if I keep it in monitor mode while calling. All 6 trunks go to the pbx.

These lines are listed on the school's bill as if they are some type of PRI (according to the lady who looked at the bill), but they are broken out into 6 individuals pairs and come from the telco block individually.

My CO knowledge is pretty poor so I'm not sure exactly what type of trunks these are. Anyone who can enlighten me on this would be greatly appreciated.

Thanks!

Also, it IS possible to call out on these trunks by dialing through the phone system, i.e. picking up line 1 on a handset. I can't get dialtone with my test set at the demarc but I can with an extension. ??

 

[Dexman]

The lines could be configured as ground start or they could be set up to receive calls, but not originate them.

If it ain't broke, I haven't fixed it yet.

 

[paterson]

The other posibility is that they are analog DID trunks.

DID = Direct Inward Dial

These trunks are inward ONLY and will deliver digits to the PBX. These digits represent the DID telephone numbers you have. The amount of digits sent on a per call basis depends on the setup from the CO. I have seen as little as the last 3 digits and up to the full 10 digits (including area code). Your PBX will be set up to receive these digits and send the call to the specific phone programmed for that DID number.



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[LAdrummer]

Thanks for your input guys. On the phone bill it lists these numbers as a "Combination Trunk".

The only reason I don't think they are a DID is that the phone system can dial out on them. Or at least I can ANI them from the front desk phone and each trunk comes up with a different number.

??

Again, my thanks for your input!

 

[Dexman]

Are they ground or loop start?

If it ain't broke, I haven't fixed it yet.

 

[Deweyhumbolt]

If you listen with butt set and hear incoming DTMF digits, it's analog DID. If you just hear ring generation, they're Ground Start.

Adversity is Opportunity

 

[ISDNman]

If you are not familiar with ground start, here is how to draw dial tone.

Put your butt set off hook and connect to the line.

Take an alligator clip lead with one end ground and tap it against one side of the line briefly with it.

If you get dial tone, dial.

If not, try hitting the grounded wire against the other side of the line momentarily.

If you get dial tone, dial.

If you ask a better question you will get a better reply. Be specific so we can help!

 

[hawks]

The only way I know to use Ground Start on these is with a T1 card. According to LAdrummer these 6 lines come via copper prs. This could be a PRI coming in that shares voice/data and broken out to analog trunks. have you tried to just go off hokk with your butt set and make a call?

 

[LAdrummer]

Thanks guys. It sounds like they might be ground start. Deweyhumbolt, I just hear ring generation when monitoring the line. Unfortunately the school is about three hours away so I won't be able to test them again until next week. I'll try to ground start them.

Here's another question.....Because the phone system (Vodavi Starplus) is able to dial out on them, I'm assuming the trunk ports on the line card are programmed to be ground start. I'm not familiar with programming the Vodavi but I can only assume that is how the phone system can dial out, if the trunks are indeed ground start.

 

[hawks]

sorry I thought I was in the Norstar forum which does not do ground start on analog trunks. I'm not sure about the Vodavi, but if these lines are truly ground start then I would say so.

 

[hawks]

Take a look at thread461-1471808 there is some pretty straight forward information there on types of trunks.

 

[KZ9Y]

SBC had combo trunks. They were ordered (about 6-7 yrs. ago)for new DID service to one of our sites. We didn't know the wrong thing was ordered until the DID card in the key system went out. Dialtone voltage fried the card. We then ordered straight DID circuits.

jva

>****

 

[KZ9Y]

Part of the previous post in error. It was ringing voltage that fried the DID card.

jva

>****

 

[jerryreeve]

whenever I see combo trunk it seems to end up for the most part being ground staart. a combo can be loop start but it is more expensive than a 1mb (pots) business line so for the most part if loop start is needed I see pots and if ground start is needed I see combo trunks.

If you look around and see a pair of wire at the cross connect board that is hooked to ground/metal conduit, waterpipe etc. and the other end is about 1/2 inch of bare copper you probably have ground start trunks on that board. (A tech in the past set up for testing and then just left the wire hanging)

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'Rule 29', "The enemy of my enemy is my enemy's enemy. No more. No less."
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JerryReeve
Communication Systems Int'l
com-sys.com