I used to deploy small portable satcom packages for a living. One of the things I was routinely asked to do was to provide local Tampa dial tone to my customers no matter where in the world they traveled. So we would connect a device known as a Multi-Rate Voice Card (essentially just a codec with a couple of compression algorithms) to the local telephone system on one side and the satcom gateway on the other (digital) side. It was configured as FXO (it was the office side of the equation). This simply told the device how to behave. That is, how to handle signaling on the 2-wire loop, such as wink-start, off hook, ring voltage, etc. On the deployed side, we would plug a telephone into a MRVC configured as FXS (it was the subscriber side of the equation). Again, this simply told the MRVC how to behave. Of course, the digital side of the FXS MRVC was connected to the digital side of the FXO MRVC via the satellite link.
Tampa_switch--(analog)FXO-MRVC(digital)--gateway--satellite--gateway--(digital)FXS-MRVC(analog)--telephone The 2-wire port on the telephone switch in Tampa knew nothing about any of this. As far as it could tell, there was a local telephone hanging off of it. I think it might be a stretch to move those FXO/FXS labels out to the telephone instruments. I always thought that it only applied to devices, usually in the middle, that needed to know how to behave. And a telephone has no identity crisis that needs to be addressed. Having said all that, I don�t see any harm in calling a telephone an FXO device, as long as it�s appreciated that FXO/FXS have more to do with defining behavior than simply applying labels. Chuck's Long Road wrote: > > Someone smarter than I made the following statements about FXO > / FXS, in > order to help me understand real world connectivity. > > That person said to think of FXO / FXS as something analogous > to DTE / DCE. > > That is, DTE connects to DCE ( and visa versa ) and that FXO > connects to FXS > ( and visa versa ) > > In other words, an analog telephone set is an FXO device, and > therefore > plugs into an FXS port. The FXS port provides the signaling to > the FXO > device. > > Similarly, a PBX, or a CO switch, for that matter, is an FXS > device that > provides signaling, and therefore plugs into an FXO port. > > This seems to fit in with what I know - that you connect a > router to a PBX > or to the telco CO switch via an FXO port, and you connect an > analogue fax > or telephone into a router FXS port. > > Any comments? Reasonable way to think of things? > > Thanks. > > Chuck > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=54382&t=54331 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
