Real-time multimedia and communication in packet networks

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Real-time multimedia and communication in packet
networks
Asterisk Dialplan and Native Database
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(No Transcript)
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Last Weeks Prac

• Create and account for your phone
• Play around with some of the settings in the
  sip.conf file

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Today's Practical

• 1) Via the dial-plan, Implement a way to record
  prompts directly from your phone through the
  extension 9100.
• 2) Implement a simple front end IVR, allowing
  callers to dial extensions, 1 for sales and
  suchlike.
• Use the show applications to find the method
  for performing recordings
• Use the show applications to find the method
  for jumping to another context
• 3) Implement a redial extension using Asterisks
  native database. i.e. extension 9200 will redial
  the last number you dialled

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Asterisk dialplan

• Dialplan routes every call in the system from its
  source through various applications to its
  destination i.e.' show applications'
• Dialplan composed of one or more contexts
• Each context contains a collection of extensions
• Each context has a unique name associated with it
• When you work, add yourname- to your contexts
  to uniquely identify them i.e. mos-first_context

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Understanding Contexts
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Basic extension context

• Diagrammatically an example extension context may
  look something like this
• In this example context (called default)
• First 4 extensions are associated with ringing
  phones for various users
• 5th extension (100) allows users to check their
  voicemail
• 6th extension (101) is associated with an audio
  conference room

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Pattern matching

• Extensions can also match patterns
• Patterns to be matched must start with an
  underscore _
• May use any of the following special characters
• X any digit from 0-9
• Z any digit from 1-9
• N any digit from 2-9
• 14-6 digits 1,4,5,6
• . matches anything (NB use with extreme caution)

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Pattern matching order

• Employing pattern matching in your Asterisk
  dialplan, while very powerful, can be tricky. It
  is easy to assume that Asterisk runs through the
  dialplan in a completely sequential manner while
  this is generally the case, it does prioritize
  patterns based on the quality of the match.
• The reason for this is simple more than one
  pattern might match a dialled number. If two
  extensions match a dialled number, Asterisk will
  always choose the better (less ambiguous) match.
  Before deciding which extension matches best, it
  processes the entire context.
• Use the dialpan show x command in the CLI to
  explore more

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Context inclusion

• One extension context can include the contents of
  another

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Asterisk predefined extensions

• Each step in an extension is typically notated as
  follows
• exten gt ltextengt,ltprioritygt,ltapplicationgt,
  (ltargsgt)
• Certain extension names are reserved for
  specialized purposes. Specifically
• s The "start" extension
• t The "timeout" extension. When a caller is in a
  voice menu and does not enter the proper number
  of digits (or enters no digits at all), the
  timeout extension is executed. If the timeout
  extension is omitted, then the caller is
  disconnected

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Asterisk predefined extensions

• i The "invalid" extension. When a caller enters
  an invalid extension number, this extension is
  executed. If omitted, the caller is disconnected
• h The "hangup" extension. If present, this
  extension is executed at the end of call (i.e.
  when the caller hangs up or is hung up upon).
  Applications executed in this extension should
  not try to do anything to the channel itself
  since it has been hung up already, but can use it
  for logging, executing commands, etc

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Dialling a phone

• Most common extension is that for dialling out
  another interface
• In this case we use the Dial application
• Dial has a number or arguments
• Do show application Dial to see more details
• exten gt 1000,1,Dial(SIP/100,20)?
• exten gt 1000,2,Voicemail(u100)?
• exten gt 1000,102,Voicemail(b100)?
• example illustrates one of the few exceptions to
  execution of an extension being out of order
• On entering the extension (priority 1) attempts
  to dial the SIP phone 1000 for a maximum of 20
  seconds
• If the phone is busy, it will jump to priority
  n101 if such a priority exists in this extension
• In this case, we have such a priority (102),
  which sends the caller to voice mailbox 1000,
  (with busy announcement)?
• If there was simply no answer (or if there was a
  busy and we didn't have a step 102), execution
  would continue at step 2, where the caller is put
  into voice mailbox 1000, (with an unavailable
  announcement)?

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Routing by callerid

• Known as the anti-ex girlfriend extension
• exten gt 100/0786346926,1,Congestion
• exten gt 100,1,Dial(Zap/1,20)?
• exten gt 100,2,Voicemail(u100)?
• exten gt 100,102,Voicemail(b100)?
• example builds upon the previous by adding a
  special rule that if the caller is 0786346926
  (routing by Caller ID is indicated by placing /
  and the Caller ID number to match immediately
  following), they are immediately presented with
  Congestion tone

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Routing by callerid

• If someone phones who doesnt send their callerid
• exten gt 100/,1,Congestion
• exten gt 100,1,Wait(3)?
• exten gt 100,2,Dial(Zap/1)?

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Routing by Time

• A lot of companies disable outgoing calls to PSTN
  after hours, we can do this easily in asterisk
• company
• exten gt _046XXXXXXX,1,Ringing()?
• exten gt _046XXXXXXX,2,GotoIfTime(830-1230
  mon-fri1-29?dial-zap,s,1)?
• exten gt _046XXXXXXX,3,Playback(so-sorry)?

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Ringing phones in sequence

• Often it is desired that a given extension first
  ring one phone, and then if there is no answer,
  ring another phone (or set of phones)?
• E.g.
• exten gt 1020,1,Dial(Zap/1Zap/2,15)?
• exten gt 1020,2,Dial(Zap/g1,15)?
• exten gt 1020,3,Playback(companymailbox)?
• exten gt 1020,4,Voicemail(100)?
• exten gt 1020,5,Hangup
• try ringing interface Zap/1
• If Zap/1 and Zap/2 are both busy, or no answer
  after 15 seconds, we try calling any other
  available phone in the Zap group for another 15
  seconds
• If still no answer (or everyone is busy) then we
  playback a message announcing that no one is
  available, and to please leave a message in
  company mailbox

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Asterisk Native Database

• Simple database resembling the Windows registry
  consisting of records of the form ltfamily/key,
  valuegt i.e. mosiuoa/foo, bar
• Developed on top of version 1 of the Berkeley
  database system
• We can list current records in the database from
  the CLI using the command database show
• We have dialplan interfaces to this database
  using the commands
• Set(DB(family/key)foo Stores a tuple into
  the database
• Set(fooDB(family/key)) Stores a database
  value into a variable
• DBDel(family/key) Deletes a tuple from the
  database
• This database and its interfaces provides us with
  data persistence, upon which we can develop
  sophisticated applications and services

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Today's Practical

• 1) Via the dial-plan, Implement a way to record
  prompts directly from your phone through the
  extension 9100.
• 2) Implement a simple front end IVR, allowing
  callers to dial extensions, 1 for sales and
  suchlike.
• Use the show applications to find the method
  for performing recordings
• Use the show applications to find the method
  for jumping to another context
• 3) Implement a redial extension using Asterisks
  native database. i.e. extension 9200 will redial
  the last number you dialled

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Real-time multimedia and communication in packet
networks
Asterisk Variables, Macros and Auto-dialing
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Yesterdays Practical

• Implement an IVR (interactive voice response) to
  route a user through a menu system using input
  from the user
• Use voice recording to store sound files that can
  be played back to the user i.e. Playback()?
• Use DB API commands to implement a simple redial
  application of last call made
• How is it going?

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Some Dialplan Questions

• Anti-in law example
• mycontext
• exten gt 101/1000,1,Congestion
• exten gt 101,2,Playback(tt-monkeys)?
• exten gt 101,3,Hangup
• main-menu
• exten gt s,1,Playback(welcome)?
• exten gt s,2,Goto(mycontext,101,1)?

the above will give congestion when 1000 calls
and terminate if anyone else calls
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Some Dialplan Questions

• Repeated extension
• default
• exten gt 101,1,SayAlpha(abc)?
• exten gt 101,1,SayAlpha(xyz)?
• exten gt 101,2,Set(TIMEOUT(digit)5)?
• exten gt t,1,Playback(vm-goodbye)?
• exten gt t,2,Hangup

asterisk plays first rule when there is a
ltexten,prioritygt clash
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Variables in the dialplan

• Asterisk makes use of global and channel specific
  variables
• Variables are expressed in the dialplan using
  foo where foo is the name of the variable
• A variable may be any alphanumeric string
  beginning with a letter, but there are some
  variables whose names have special meanings.
  Specifically
• CONTEXT - The current context
• EXTEN - The current extension
• EXTENx - The current extension with x leading
• digits dropped
• PRIORITY - The current priority
• CALLERID - The current Caller ID (name and
  number)?
• CALLERIDNUM - The current Caller ID number
• CALLERIDNAME - The current Caller ID name

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Variables

• Global variables specified in the globals
  section of the dialplan or can be set using the
  SetGlobalVar command
• Channel variables are set using Set command in
  the dialplan and are accessible to only one
  channel
• Environment variables allow Asterisk to get
  access to UNIX variables using the ENV(foo)
  notation
• variables
• exten gt 100,1,SetGlobalVar(FOO1011)
• exten gt 100,2,Dial(SIP/FOO)
• exten gt 100,3,Set(FEE7521)
• exten gt 100,4,Dial(SIP/FEE_at_sip.ict.ru.ac.za,20
  )
• exten gt 100,5,NoOp(ENV(HOSTNAME)

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Including contexts

• One context can include zero or more other
  contexts, optionally with a date/time limitation
• Contexts are included in the order they are
  listed
• The format for include is
• include gt ltcontextgtlthoursgtltweekdaysgtltmonthday
  sgtltmonthsgt
• Where
• ltcontextgt is the context to be included
• lthoursgt are the hours in which this include is
  considered valid (in the form of a range, in
  military time, e.g. 900-1700)?
• ltweekdaysgt are the days of the week considered
  valid (e.g. mon-fri)?
• ltmonthdaysgt are the days of the month considered
  valid (e.g. 22-25)?
• ltmonthsgt are the months considered valid

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Including contexts

• newyears
• exten gt s,1,Playback(happy-new-years)?
• daytime
• exten gt s,1,Dial(Zap/1,20)?
• nighttime
• exten gt s,1,Playback(after-hours-msg)?
• default
• include gt newyears1jan
• include gt daytime900-1700mon-fri
• include gt nighttime

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Using Macros

• While Asterisk extension logic is very flexible,
  it can also be very verbose when creating many
  extensions which are similar
• For simplicity, we can take advantage of macros
  which simplify dialplans and make it easier to
  modify flows on a large scale
• Macros are implemented by creating an extension
  context whose name begins with macro-, followed
  by the name of the macro
• Execution begins at the s extension and ends as
  soon as the extension drops to a location that is
  no longer within the macro

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Using Macros

• Macros define some useful local variables,
  specifically
• MACRO_EXTEN - The extension calling the macro
• MACRO_CONTEXT - The extension context calling
  the macro
• MACRO_PRIORITY - The active priority when the
  macro was called
• MACRO_OFFSET - If set, causes the macro to
  attempt to return to n MACRO_OFFSET
• ARGn - The nth argument passed to the macro

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Using Macros

• macro-oneline
• Standard one-line phone.
• ARG1 - Device to use
• exten gt s,1,Dial(ARG1,20)?
• exten gt s,2,Voicemail(uMACRO_EXTEN)?
• exten gt s,3,Hangup
• exten gt s,102,Voicemail(bMACRO_EXTEN)?
• exten gt s,103,Hangup
• macro-twoline
• Standard two-line phone.
• ARG1 - First phone
• ARG2 - Second phone
• exten gt s,1,Dial(ARG1,20)?
• exten gt s,2,Voicemail(uMACRO_EXTEN)?
• exten gt s,102,Dial(ARG2,20)?
• exten gt s,103,Voicemail(bMACRO_EXTEN)?

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Using Macros

• After doing the complex work of defining the
  oneline macro for a single line phone and the
  twoline macro for a two-line phone
• implementing the default context becomes
  extremely easy, and each extension requires only
  a single line instead of several similar lines

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Auto-Dial

• We can use s auto-dial feature to create
  outgoing calls from external applications
• Typically done by dumping a specially formatted
  file in /var/spool/asterisk/outgoing
• Can also be done via Manager Interface (more on
  this at a later date)?

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Typical Call File

• Channel SIP/1000
• MaxRetries 2
• WaitTime 10
• RetryTime 10
• Context mos-callme
• Extension 500
• Priority 1

we can also use the linux command touch -t
YYYYMMDDhhmm file to schedule callme in the
future
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Today's Practical

• Hope you didnt have any plans for the weekend!
• Create a calculator application using the
  Asterisk dialplan
• E.g. phone an extension
• answers and provide an IVR menu saying press 1
  to go to the calculator, 2 to go somewhere else,
  and 3 to go somewhere further
• If I press 1 must be routed to calculator where
  I am prompted to choose to go to multiplication
  menu, division menu, add menu or subtraction menu
• 1,2,3,4
• Within each menu prompt user for expression
  separated by star ()?
• So in addition menu, pressing 10020 should
  return 120
• While in multiplication menu pressing 10020 will
  return 2000
• Results can be played using Festival or text2wave
• After each result should have option of another
  operation or going to one of the other menus
  (-/)?
• Remember to check out http//www.voip-info.org/ -
  Check out the Cut function!