Page 190 - Asterisk™: The Future of Telephony

exten => 678,n,Set(DB(test/count)=1)
exten => 678,n,Goto(1)
exten => 678,n(continue),NoOp()
exten => 678,n,SayNumber(${COUNT})
exten => 678,n,Set(COUNT=$[${COUNT} + 1])
Now that we’ve incremented COUNT, let’s put the new value back into the database.
Remember that storing a value for an existing key overwrites the previous value:
exten => 678,1,Set(COUNT=${DB(test/count)})
exten => 678,n,GotoIf($[${ISNULL(${COUNT})}]?:continue)
exten => 678,n,Set(DB(test/count)=1)
exten => 678,n,Goto(1)
exten => 678,n(continue),NoOp()
exten => 678,n,SayNumber(${COUNT})
exten => 678,n,Set(COUNT=$[${COUNT} + 1])
exten => 678,n,Set(DB(test/count)=${COUNT})
Finally, we’ll loop back to the first priority. This way, the application will continue
counting:
exten => 678,1,Set(COUNT=${DB(test/count)})
exten => 678,n,GotoIf($[${ISNULL(${COUNT})}]?:continue)
exten => 678,n,Set(DB(test/count)=1)
exten => 678,n,Goto(1)
exten => 678,n(continue),NoOp()
exten => 678,n,SayNumber(${COUNT})
exten => 678,n,Set(COUNT=$[${COUNT} + 1]
exten => 678,n,Set(DB(test/count)=${COUNT})
exten => 678,n,Goto(1)
Go ahead and try this example. Listen to it count for a while, and then hang up. When
you dial this extension again, it should continue counting from where it left off. The
value stored in the database will be persistent, even across a restart of Asterisk.
In the next example, we’ll create dialplan logic around the BLACKLIST() function, which
checks to see if the current Caller ID number exists in the blacklist. (The blacklist is
simply a family called blacklist in the AstDB.) If BLACKLIST() finds the number in the
blacklist, it returns the value 1, otherwise it will return 0. We can use these values in
combination with a GotoIf() to control whether the call will execute the Dial()
application:
exten => 124,1,GotoIf($[${BLACKLIST()]?blocked,1)
exten => 124,n,Dial(${JOHN})
exten => blocked,1,Playback(privacy-you-are-blacklisted)
exten => blocked,n,Playback(vm-goodbye)
exten => blocked,n,Hangup()
To add a number to the blacklist, run the database put blacklist number 1 command
from the Asterisk command-line interface.

162 | Chapter 6: More Dialplan Concepts