Questions about signaling options with T1/E1

Unanswered Question
Jun 4th, 2007

I'm reading through CVOICE study guide and just trying to get my head around some of the concepts. Can anyone tell me if I've got this right?

1) If you configure a T1 for or E1 controller with the command "ds0-group" does this inherently imply that you are using CAS signaling on the digital circuit?

2) I'm noticing that all the options for the "signal-type" parameter in the "ds0-group" command (listed below) seem to be signalling types that I would normally associate with analog interfaces. Does this imply that all CAS signaling methods on a T1/E1 are just digital emulations of analog signaling methods or am I thinking about this the wrong way?

e&m-fgb E & M Type II FGB

e&m-fgd E & M Type II FGD

e&m-immediate-start E & M Immediate Start

fgd-eana FGD Exchange Access North American

fgd-os FGD Operator Services

fxs-ground-start FXS Ground Start

fxs-loop-start FXS Loop Start

none Null Signaling for External Call Control

r1-itu R1 ITU

sas-ground-start SAS Ground Start

sas-loop-start SAS Loop Start

3) From my ref book examples of CCS signaling include:

- Proprietary Implementations

- ISDN PRI or BRI (Has its own call control protocol called Q.931)

- QSIG (Only implemented on ISDN PRI interfaces)

- DPNSS (Operates over standard ISDN physical interfaces)

- SS7

So... The examples I've seen seem to suggest that if you want CCS signaling on a T1/E1 (and I understand it's the modern prefered method) it impies the use of ISDN service from your provider and you configure your T1/E1 as a PRI to match. If I'm undertanding the option right with ISDN PRI you can then choose from several differnet call control protocols including Q.931, QSIG, or in rare circumstances DPNSS??? I presume it would depend on what you're connecting too?

To sum up... a T1 configured as ISDN PRI implies use of CCS and allows you to choose from various digital signaling protocols and lack of ISDN on a T1/E1 implies use of CAS with a choice of older analog protocol emulated digitally. Is that an accurate statement?

Thanks much for any assistance and yes I will rate responses :)

I have this problem too.
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beth-martin Fri, 06/08/2007 - 12:16

QSIG protocol is basically used to connect the Gateway to the PBX using T1/E1


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