[Asterisk-Users] TDM400P specs clarification

[Rich Adamson]

> Hello,
>       I need some clarification on TDM400P.
> 
> While browsing the Digium site I see that the TDM400P wildcard 
> is being used as base card for other TDM series cards.
> 
> I wanted to know what basically the TDM400P card offers. 
> If you see the specs it says :
> 
> " The Wildcard TDM400P is a half-length PCI 2.2 compliant card 
> that supports from one to four telephone interfaces for connecting 
> analog telephones or analog lines to a PC "
> 
> The term : 
> 
> " one to four telephone interfaces for connecting 
> analog telephones or analog lines "
> 
> In terms of FXO and FXS what does it mean. I can see that
> it has four RJ 11 sockets.
> 
> How will you decide which of the four interface to use for
> what. I mean FXO or FXS.

The fxo modules are designed to interface to a pstn line (where
ringing comes from the central switching office).

The fxs modules are designed to have standard telephone sets
plugged into them, and the module provides ringing voltage to
the telephone.

On the digium web site, a tdm04b is the tdm card with four fxo
modules installed. The tdm40b is the same tdm card with four
fxs modules installed. The tdm22b has two fxo and two fxs modules.

If you incorrectly connect a fxs module to a pstn line, you will
likely blow the module making it useless.