Analog interfaces FXS-FXO nd E&M

[23gorele76]

Who can detaily explain where we should use FXS, FXO and E&M? What are the differencies between them?

For example: If two of WAN sides routers have got only FXS ports that directly connected to PBXs, can we not call other sides PBX outside? So we need at least one FXO port?

 

[qz01gs]

Check this

http://www.cisco.com/en/US/tech/tk652/tk653/tk754/tsd_technology_support_sub-protocol_home.html

 

[Phoneguy69]

An FXO port in a router is for a copper lines.
In a VoIP environment/ say a company only has 3 lines- they can bring there copper lines into a router and can be used with the VoIP phones attached to that gateway.

An FXS port is a single line connection say a FAX or MODEM at that particular site andis soley used for a single line device. Thes S/L devices utilize the FXO ports to gain access to the PSTN.

Hope this helps

 

[mgrieb]

FXS and and FXO are complimentray interfaces similar to the old modem DCE/DTE...

FXS - (Forign exchange Station) supplies dial-tone to an analog station device such as a FAX, modem, or "kitchen" phone.. FXS also generates 90Vac ringing to teh station device..

FXO - (Forign exchange Office) receives dial-tone and is to be connecetd to a central-office line...The FXO also recieves the 90Vac ringing which "wakes-it-up" so that it can notify common control of an incoming call..