Datasets:
Squidnutz
/
extractedtest

Dataset card Data Studio Files
xet
 Community
1
text
stringlengths
0
152
you can actually pass either one, two, or three arguments to the
application. If you pass a single argument, Asterisk will assume it’s
the destination priority in the current extension. If you pass two
arguments, Asterisk will treat them as the extension and the prior‐
ity to go to in the current context.
In this example, we’ve passed all three arguments for the sake of
clarity, but passing just the extension and priority would have had
the same effect, since the destination context is the same as the
source context.
Handling Invalid Entries and Timeouts
We need an extension for invalid entries. In Asterisk, when a context receives a
request for an extension that is not valid within that context (e.g., pressing 9 in the
preceding example), the call is sent to the i extension. We also need an extension to
handle situations when the caller doesn’t give input in time (the default timeout is 10
seconds). Calls will be sent to the t extension if the caller takes too long to press a
digit after WaitExten() has been called. Here is what our dialplan will look like after
we’ve added these two extensions:
[TestMenu]
exten => start,1,Answer()
same => n,Background(enter-ext-of-person)
same => n,WaitExten(5)
exten => 1,1,Playback(digits/1)
same => n,Goto(TestMenu,start,1)
exten => 2,1,Playback(digits/2)
same => n,Goto(TestMenu,start,1)
exten => i,1,Playback(pbx-invalid)
same => n,Goto(TestMenu,start,1)
exten => t,1,Playback(please-try-again)
same => n,Goto(TestMenu,start,1)
Using the i11 and t extensions makes our menu a little more robust and user-friendly.
That being said, it is still quite limited, because outside callers still have no way of
connecting to a live person. To do that, we’ll need to learn about the Dial()
application.
11 The i extension is for catching invalid entries supplied to a dialplan application such as Background(). It is
not used for matching on invalidly dialed extensions or nonmatching pattern matches.
92
|
Chapter 6: Dialplan Basics
Using the Dial() Application
One of Asterisk’s most valuable features is its ability to connect different callers to
each other. While Asterisk currently is used mostly for SIP connections, it supports a
wide variety of channel types (from Analog to SS7, and various old VoIP protocols
such as MGCP and SCCP). Asterisk takes much of the hard work out of connecting
and translating between disparate networks. All you have to do is learn how to use
the Dial() application.
The syntax of the Dial() application is more complex than that of the other applica‐
tions we’ve used so far, but it’s also where much of the magic of Asterisk happens.
Dial() takes up to four arguments, which we’ll look at next.
The syntax of Dial() looks like this:
Dial(Technology/Resource[&Technology2/Resource2[&...]][,timeout[,options[,URL]]])
Put simply, you tell Dial() what channel12 you want to send the call out to, and set a
few options to tweak the behavior. The use of Dial() can get complex, but at its most
basic, it’s that simple.
Argument 1: destination
The first argument is the destination you’re attempting to call, which (in its simplest
form) is made up of a technology (or transport) across which to make the call, a for‐
ward slash, and the address of the remote endpoint or resource.
These days, you’re most likely to be using PJSIP as your channel
type, but in the not-too-distant past, common technology types
also included DAHDI (for analog and T1/E1/J1 channels), the old
SIP channel (prior to PJSIP), and IAX2.13 If you’re looking at an
older dialplan, you may see some of these other protocols repre‐
sented. Going forward, only PJSIP and DAHDI are recommended
and maintained.
Let’s assume that we want to call one of our PJSIP channels named SOFTPHONE_B. The
technology is PJSIP, and the resource (or channel) identifier is SOFTPHONE_B. Simi‐
larly, a call to a DAHDI device (defined in chan_dahdi.conf) might have a destination
12 Or channels, if you want to ring more than one at a time.
13 IAX2 (pronounced “EEKS”), is the Inter Asterisk Exchange protocol (v2). In the early days of Asterisk it was
popular for trunking, as it greatly reduced signaling overhead on busy circuits. Bandwidth has become far less
expensive, and SIP protocol has become nearly ubiquitous. The IAX2 protocol is no longer actively main‐
tained, but it still retains some popularity for its ability to traverse firewalls, and a few carriers might still sup‐
port it. However, its use is deprecated, and in fact discouraged.
Building an Interactive Dialplan