Switching to VoIP

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Chapter 3: Linux as a PBX

We’ve chosen the X100P for connecting our VoIP server to the PSTN because it’s

less costly than the TDM400P. Of course, you could substitute a TDM400P card

with an FXO module in place of the X100P. Asterisk distinguishes little between a

TDM400P connected to a POTS line and an X100P connected to a POTS line, so

either card should work fine for most of our projects.

If you decide to use the TDM400P instead of the X100P for your VoIP test server, it

needs a minimum of one FXO interface module, connected to a POTS line as if it

were a single-line X100P card.

The TDM400P has RJ45-looking sockets like an Ethernet card—but

don’t connect them to Ethernet, or you could damage the card, your

PC, or your Ethernet switch!

Other Interfaces

Besides the X100P and the TDM400P, Digium offers some other specialized inter-

face cards. Other vendors make interface devices that can be used with Asterisk, too.

Table 3-1 describes some of the devices that are available, including the X100P and

TDM400P.

Table 3-1. Some Asterisk-compatible VoIP interface devices

Device Vendor PC interface

Telephony

interface

Purpose

X100P Digium PCI RJ11-style Connect an analog phone

line (trunk)

TDM400P Digium PCI Quad RJ45-style Connect analog phone lines

(trunks) or analog

endpoints

TE400 Series Digium ...