FXS-FXS, FXS-FXO, FXO-FXO, E&M-E&M

[kobchai7037]

Hello,

Could anybody please explain to me what is the different, advantages, and disadvantages between each combination mentioned in the title?

Thank you

[jtufail]

Simply speaking

FXS is the foreign exchange station, provides ring generation and battery and you can hook up analog devices such as phones fax etc to it.

FXO is Foreign exchange Office. It does not provide any battery and hence you can not attach an anlog device to it.

Both the FXO and FXS use either loop start of ground start signaling and only use two wires.

E&M interfaces use E and M leads for detection of line signaling and use the other 6 wires depending on the type you are using for audio.

Please review the following documents for greater details on these modules:

For FXS:

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

For FXO

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

For E&M

http://www.cisco.com/en/US/products/hw/modules/ps2641/products_tech_note09186a0080094ab9.shtml