From: Juan Alcaide (jalcaide@xxxxxxxxx)
Date: Tue Oct 02 2001 - 18:07:23 GMT-3
Maybe this will make it clearer.
Tel1--FXS-ROUTER1-FXO----FXS-ROTER2-FXS-Tel2
FXS can connect FXO. But only FXO could start the call with an outgoing
telephone number.I'd like to connect ROUTER1-ROUTER2 without using E&M
interface.
What I thought it could happen if Tel2 dials to Tel1 is that ROUTER2
(FXS) would start a call to ROUTER1(FXO) This (actually happens). Then,
"somehow" FXO in ROUTER1 should listen for aditional numbers to route to
Tel1.
I believe ROUTER1 would act like a PBX here. And I think PBXs do not need
to have E&M interfaces always, right?
-Juan
On Tue, 2 Oct 2001, Jay Hennigan wrote:
> On Tue, 2 Oct 2001, Juan Alcaide wrote:
>
> > So if you have
> >
> >
> > Tel1--ROUTER-FXO----FXS-PBX---(cloud)-Tel2
> >
> > With my config:
> > Tel1 can dial Tel2 (FXO says to FXS I want to dial Tel2)
> > Tel2 cannot dial Tel1 (FXS can not say to FXO I want to dial Tel1)
>
> FXO is not intended to connect to a telephone, but to a telephone line.
>
> If you connect a POTS dialtone to the FXO side instead of Tel1 you should
> have a working setup. Conversely, move the PBX to the other side of your
> diagram, as the FXS side is happy talking directly to a telephone.
>
> Keep the following in mind and you should be OK:
>
> An FXS port:
>
> * connects to a telephone
> * sources battery power to the telephone
> * provides dialtone
> * provides ringing voltage
> * accepts dialed digits from the telephone
> * "looks like" a central office line
>
> An FXO port:
>
> * connects to a telephone line
> * sinks (consumes) battery power from the line
> * "hears" dialtone
> * accepts ringing voltage
> * sends dialed digits out to the line
> * "looks like" a telephone
>
> Sending digits into an FXO interface from the outside would be like
> someone calling you on the phone and playing touchtones into your ear,
> it won't cause anything interesting to happen from a network standpoint
> and it will annoy ther person called. Voice-mail and IVR are quasi-
> ecxeptions in that tones played into such devices after a call is
> answered can cause things to happen, but not in terms of the call
> placed to the voice-mail or IVR system itself.
>
> To configure a setup where the Cisco VoIP works as an "intercom" with
> two telephones that can dial each other, you should use two FXS ports.
>
> If what you have in your home lab is an FXS and FXO and you want to
> practice, configure the FXO as a an outbound POTS call leg either to
> a station port on a PBX or a plain old phone line.
>
> --
> Jay Hennigan - CCIE #7880 - Network Administration - jay@west.net
> NetLojix Communications, Inc. - http://www.netlojix.com/
> WestNet: Connecting you to the planet. 805 884-6323
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