Switching to VoIP

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Chapter 17: Asterisk Reference

Dialing/CallwaitCAS: 0/0

Default law: ulaw

Fax Handled: no

Pulse phone: no

Echo Cancellation: 128 taps, currently OFF

Actual Confinfo: Num/0, Mode/0x0000

There are many channel-specific settings, most of which are user-definable. You can

see from this list that, even within the scope of a single Zaptel channel, Asterisk is

extremely flexible. In our test server, this channel is an FXO channel—that is, a

channel that connects to the telephone company. In order to interact correctly with

the phone company’s switch, the X100P (or other compatible) interface has to use

FXS signaling, so that, to the phone company, it appears to be a regular telephone

answering the line and not a newfangled Asterisk server (FXO/FXS signaling was

introduced in Chapter 4). Other types of channels (SIP, H.323, etc.) have their own

channel-specific settings.

Inspecting the Dial-Plan

The show dialplan CLI command can be used two ways: showing the entire system-

wide dial-plan, or only showing a specific context or extension. Here’s the output for

a small, but complete, dial-plan:

pbx*CLI> show dialplan

[ Context 'default' created by 'pbx_config' ]

'3101' => 1. Dial(SIP/3101@10.1.1.101) [pbx_config]

2. Voicemail(u4101) [pbx_config]

'3102' => 1. Dial(SIP/3102@10.1.1.102) [pbx_config]

2. Voicemail(u4101) [pbx_config]

'3103' => 1. Dial(SIP/3103@10.1.1.103) [pbx_config]

2. Voicemail(u4101) [pbx_config]

'8500' => 1. VoiceMailMain( ) [pbx_config]

'_9NXXXXXX' => 1. Dial(${PSTN}/{EXTEN:1}) [pbx_config]

2. Congestion( ) [pbx_config]

Ignore pattern => '9' [pbx_config]

[ Context 'incoming' created by 'pbx_config' ]

's' => 1. Answer( ) [pbx_config]

2. Dial(SIP/3103@10.1.1.103|30) [pbx_config]

3. Voicemail(u4101) [pbx_config]

4. Hangup( ) [pbx_config]

In the default context, several extensions are configured to ring calls on specific SIP

telephones with static IP addresses and an extension pattern that matches outbound

calls. The 8500 extension is one that allows private users of the Asterisk system to

access the voice mail management greeting.