Using NM-HDA and VIC-2E/M

Unanswered Question
Jan 21st, 2008

Can I connect VIC-2E/M with an NM-HDA-4FXS and EM-HDA-4FXO ?

Thanks

I have this problem too.
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pcameron Mon, 01/21/2008 - 03:21

No , the interfaces have completely different physical characteristics and cannot be directly connected to each other.

FXS and FXO are two wire interfaces and relay on the presence or absence of loop current.

FXS supplies battery feed (-48Vdc) and ring signal (80Vac).

FXO terminates battery feed and senses ring signal.

FXS interworks to FXO

E&M normally has a TX pair and a RX pair - the audio signals are physically seperated> (there are two wire variants where the TX and RX are passed on the same pair)

E&M has other control leads - E lead, M lead , Signal Battery and Ground.

E&M passes call states (on hook, off hook, answer, disconnect) via the control leads and passes signaling and speech information on the audio pairs.

Here is some background -

http://www.cisco.com/en/US/tech/tk652/tk653/technologies_tech_note09186a0080094ab9.shtml

http://www.cisco.com/en/US/products/hw/routers/ps274/products_tech_note09186a00800b53c7.shtml

http://www.cisco.com/en/US/tech/tk652/tk653/technologies_tech_note09186a0080094fac.shtml

connect101 Mon, 01/21/2008 - 05:23

Thanks for the reply,

Can I connect the two router with the E&M cards?

I explain :

The first router have four VIC-2E&M cards.

So I want to use it by connecting them with a Cisco call Manager router.

Is it possible? If possible ho to do it?

pcameron Mon, 01/21/2008 - 06:01

Sure you can.

The easiest way is to use the good old Cisco console 'roll over' cable ... Because of the way the cable is wired and the E&M port pinouts, this cable swaps the E lead to the M lead , the M lead to the E lead on either side.

Refer here for the basics of E&M interfaces -

http://www.cisco.com/en/US/products/hw/gatecont/ps2250/products_tech_note09186a008009452e.shtml

And here for a description of how to use the Console cable to connect two E&M ports -

http://www.cisco.com/en/US/tech/tk1077/technologies_tech_note09186a0080093f5e.shtml#rollovercable

If you want to use a 4 wire connection between E&M ports , the cable would be

1 ---- 8

2 ---- 7

3 ---- 5

4 ---- 3

5 ---- 6

6 ---- 4

7 ---- 2

8 ---- 1

in your case , router A would be connected to router B, so use the POTS dial peer on router to send the call to Router B, and use the VOIP dial peer to send the call to the call manager.

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