Difference betwen E1 G703 and E1

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Oct 13th, 2009
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Can someone tell me the difference between two E1 cards in a router - E1 RJ4 and E1 G703- not neccessary the technical stuff just can I use either of them for a 30 Channel E1 link and if so is there a difference in the configuration . I have a spare G703 in a "lab" and can I use it connecting to a Q sig link - MGCP, H323


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Wilson Samuel Tue, 10/13/2009 - 05:03
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Even I was once hunting for the same question, though I'm not sure I got the clear and specific answer about it, however definitly what I got is certainly somewhat helpful


In a nutshell it explains that, G.703 E1 is like a T1 CAS compared to a T1 PRI (in some crude way) and further more the G.703 is very specific in terms of communication electronics, cabling, clocking etc for the E1, where as E1 is a general term which could be "Balanced" or "Unbalanced" or "Framed" or "Unframed" depending on what one want or what a SP provides.

As far as Lab is concerned, it wont make much of a difference anyways wrt to IPT.


Sam Wilson

Hythim Ali El Hadad Tue, 10/13/2009 - 05:16
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I think we can talk from another side,

from the modem prespective

G703 modems & V35 modems

The first one is for the voice E1's which give you 30 cahnnels

and the E1 card interface is RJ45

the 2nd one is for the E1 data which is used for leased lines

It is connected to the wic 1T/2T on the router,no E1 cards needed

Wish this be helpful

paolo bevilacqua Tue, 10/13/2009 - 05:59
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That is not correct.

G.703 is the ITU standard that defines electrical encoding for a variety of digital circuits, among these, E1 and T1. It does not discuss any upper layer or channelization.

G.704 defines framing and channelization for the same type circuits, so it defines channelized E1, and T1, although the latter has also equivalent north American standards.

However in cisco and industry parlance, G.703 often refers to unframed E1 circuits of 2,048 kbps, not usable for traditional voice.

So in other words, all T1 and E1, be that CAS, PRI or data are G.703 compliant.


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