2-FXS VoIP adapter versus 2-port FXO VoIP adapter?

FXS and FXO are things on the two ends of the phone cord, S for Station and O for central Office. A phone is a station, so if you want it to work, the other end of the cord better be an FXO.

Actually, if he wants to connect a phone to a router/gateway, he'll do that with the FXS ports. FXO would be for inbound/outbound calling via analog lines/trunks to and from the CO.

And just to make it even more confusing the home VOIP adapters are sometimes (incorrectly) labeled with the names of the interface that they are meant to connect to. When you look at the Sipura marketing material they refer to the various units as having either "2 FXS's" for the two phone version or "1 FXS, 1 FXO" for the version that splices between your CO and your phone. The FXO interface they are referring to is clearly an interface that is meant to *connect* *to* an FXO (but obviously is an FXS itself).

I'm not sure how the average person is expected to piece that alphabet soup all together.

-wolfgang

Sure -- But you have to realize that this is pretty standard for PC grade hardware. For many moons parallel ports had little "printer" icons, PS/2 ports have little keyboard and mice icons, modems have a jack where you connect the line-in, and one for the phone.

Home VoIP adapters are targeted towards that market, rather then the more technical market that would want to know what a jack IS rather then what it connects to.