Switching to VoIP

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Asterisk Channels

|

411

WaitMusicOnHold

WaitMusicOnHold(seconds)

Identical to Wait( ), but plays the music-on-hold class associated with this call or

context while the caller is waiting.

Zapateller

Zapateller( )

Sends the do-not-call signal to incoming callers.

ZapBarge

ZapBarge(channel)

Allows caller to clandestinely listen in on another channel’s call in progress, as long

as it’s a Zaptel channel. Neither party in the conversation will know that the call is

being monitored by the “barging” caller. If you don’t provide a channel name, the

caller will be prompted for one. Entering 1# would listen in on Zap/1, while enter-

ing 3# would listen in on Zap/3.

ZapScan

ZapScan( )

Scans Zaptel channels to monitor calls. Pressing # moves to the next channel. Press-

ing the star key (

*) exits to the next priority.

Asterisk Channels

While extensions.conf is the main place Asterisk’s dial-plan is configured, other files

are needed to set up the VoIP and TDM interfacing necessary to allow the Asterisk

server to communicate with the outside world. These files include zapata.conf,

zaptel.conf, and sip.conf.

Zaptel Channels

Digium’s Wildcard interface cards enable legacy channels so Asterisk can communi-

cate using T1s and analog phones or POTS lines. Chapter 3 describe how to obtain

and install Asterisk with the Linux drivers for a kernel interface to the Wildcard

product line, an interface known as Zaptel.

Once installed, the ztcfg program, included with the drivers, can be used to query the

zapata.conf file to validate your Zaptel channel configuration. These files determine:

• The ID number for each legacy interface channel that will be referenced in

extensions.conf. Each card must be assigned a unique number.

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

412

|

Chapter 17: Asterisk Reference

• The kind of signaling that each legacy interface card will use (T1, FXO, FXS, etc.).

• What localized ringback tones will be used with each interface card. English

ringback tones sound different than American ones. Consult the latest Zaptel

build to find out which localities are currently supported.

• What telephony features are enabled on each channel (caller ID, autocallback,

etc.).

• How distinctive ringing is handled on trunks and how it is generated for analog

phones connected to the server.

Executing /usr/sbin/ztcfg will tell you if the zaptel.conf file is valid for the hardware

you’ve got installed. If ztcfg exits without giving you any output, your configuration

is valid. If you’d like to see more verbose output, add a

-v or -vv.

Using analog interfaces with Asterisk

The zaptel.conf file contains information used by Asterisk to determine what inter-

face modules you’re using with your Wildcard hardware. Each section in the zaptel.

conf file describes a single interface’s configuration. The following example zaptel.

conf is for a system with two X100P cards and one TDM400P card with four FXS

interfaces on it. It can support two POTS lines and four analog telephones:

; zaptel.conf example

loadzone = us

defaultzone=us

; X100P cards

fxsks=1,2

; TDM400P card

fxoks=3-6

Depending upon the analog interface cards you’ve selected, you’ll need configura-

tion entries similar to those in Table 17-1.

Table 17-1. zaptel.conf analog interface configuration combinations

Card Module configuration zaptel.conf entry

1 X100P card 1 FXO interface fxsks=1

2 X100P cards 1 FXO interface on each card fxsks=1-2

1 S100U card 1 FXS interface fxoks=1

2 S100U cards 1 FXS interface on each card fxoks=1-2

1 TDM400P card 4 FXO interfaces fxsks=1-4

1 TDM400P card 4 FXS interfaces fxoks=1-4

1 TDM400P card 2 FXO interface, 2 FXS interfaces fxsks=1-2