Questions about signaling options with T1/E1

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Jun 4th, 2007
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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 :)

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beth-martin Fri, 06/08/2007 - 12:16
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QSIG protocol is basically used to connect the Gateway to the PBX using T1/E1

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