My presentation of the Asterisk-Java framework and Click-to-Call service I developed to The Groovy Users of Minnesota technology group.

1. VoIP using Groovy
Building a “Click to Call” web service in
Groovy using Open Source Software.
Justin Grammens
Localtone Interactive
justin@localtone.com

2. But First
A lot of background on Asterisk,
VoIP, Open Source Telephony...
and a little of who I am.

3. About Me
Interested and developing applications using
Asterisk for more than a year.
Created screencasts for how to get started with
Asterisk and Adhearsion.
Developed an application for GeekSquad to
handle computer repairs
Currently developing a phone voting interface for
Localtone Radio

4. VoIP is NOT About Cheap
Phone Calls
Other companies are already
doing this cheaper and better.

5. VoIP Applications!
It's about the applications
that we can build!

6. What We Will Cover
What is Asterisk?
➢
What is a VoIP application?
➢
Why build it now?
➢
Asterisk-Java
➢
Click to Call Web Service
➢

7. Asterisk
+ Open Source Private Branch Exchange (PBX).
➢
Handles calls over ethernet or RJ11 (phone line).
+ Very powerful and flexible. I call Asterisk not
➢
just a PBX, but a telephony platform.
+ Relatively stable and scalable.
➢
- Messy to deal with in terms of extending
➢
functionality.
+++ Free!
➢

8. Asterisk : Terminology
Channel – A channel is what can setup and
➢
receive calls.
Dialplan – Script of what to do with a call. Written
➢
in the asterisk macro language.
AGI – Stdin/out TCP method allowing external
➢
applications to dynamically write dialplans.
AMI – Allows sending of commands and listen
➢
for stateful events.

9. VOIP / Web Analogy
Technology Web VOIP
HTTP
Protocol SIP – Industry Standard
FTP IAX – Asterisk Specific
RTP H.323 – Obsolete
Jingle – Gtalk
Skype - Proprietary
gzip, jpg, gif, g.711 – high bandwidth
Codec
mp3, ogg, wma, gsm – medium bandwidth
flv, mpeg, avi g.729 – low bandwidth
Apache / Tomcat Asterisk, Freeswitch
Server
AGI – Asterisk Gateway
Interactivity Interface
CGI
AMI – Asterisk Manager
Interface

10. What is a VoIP Application
Same applications we typically develop, but the
website can interface with voice and phones.
User's send commands using the dialpad of
their phone.
Users see the application change either on their
phone or on the internet. It's all just data!

11. Why Now?
Only recently has good Open Source Software
➢
been developed ( Grails / Groovy / Asterisk ).
Telecoms are slow to react.
➢
Few applications merge voice and web.
➢
Cell phone are everywhere!
➢

12. Why Now?
2.7 Billion mobile phones. 1.4 Billion fixed-lines.
➢
Users can access your application by any
➢
standard home phone.
Still hundreds of millions of phones that don't
➢
have an internet browser.
Most phone users can be identified by a
➢
standardized numerical system.

13. Typical Voice System
VOIP
Clients SIP
Grails
/
Origination/
AGI /
PSTN Termination Asterisk
SIP / IAX AMI
Asterisk
Network Server - Java
Server
Libs
/
Tomcat
Analog
PSTN Zaptel
Interface
Network / Other
Card

14. Asterisk Dialplan Language
[demo] ; Sample from Asterisk configuration extensions.conf file
;
; We start with what to do when a call first comes in.
;
exten => s,1,Wait(1) ; Wait a second, just for fun
exten => s,n,Answer ; Answer the line
exten => s,n,Set(TIMEOUT(digit)=5) ; Set Digit Timeout to 5 seconds
exten => s,n,Set(TIMEOUT(response)=10) ; Set Response Timeout to 10 seconds
exten => s,n(restart),BackGround(demo-congrats) ; Play a congratulatory message
exten => s,n(instruct),BackGround(demo-instruct); Play some instructions
exten => s,n,WaitExten ; Wait for an extension to be dialed.
exten => 2,1,BackGround(demo-moreinfo) ; Give some more information.
exten => 2,n,Goto(s,instruct)
exten => 3,1,Set(LANGUAGE()=fr) ; Set language to french
exten => 3,n,Goto(s,restart) ; Start with the congratulations
exten => 1000,1,Goto(default,s,1)

15. Difficulties in Asterisk
Conditional Loops Error Handling
➢ ➢
Complex Data Date and time
➢ ➢
Structure handling
Database / LDAP RegEx Pattern
➢ ➢
Integration Matching
Extending the Variables
➢ ➢
language Object Oriented
➢
Portability - Asterisk Design
➢
v.s Freeswitch, etc.

16. Java / Asterisk Integration Tools
Asterisk-Java project
➢
Started in 2005.
➢
➢ Provides support for AGI and AMI.
➢ Open Source library.
➢ Runs in the JVM, so it's accessible via
Groovy.
➢ Have used it via JRuby as well.
➢ Cross platform.

17. Asterisk-Java
Put the line below in extensions.conf
Tells Asterisk to process all calls by our
Asterisk-Java process
exten =>
_X.,1,Agi(agi://127.0.0.1/hello.agi)
or... when extension 888 is dialed.
exten =>
888,1,Agi(agi://127.0.0.1/hello.agi)

18. AGI Topology
Cell
Origination/
Phone
Asterisk
Termination AGI
Java
Server StdOut
Asterisk
PSTN Process
Internet
extensions
.conf
AGI
StdIn

19. Asterisk – Groovy AGI
import org.asteriskjava.fastagi.*
public class HelloAgiScript extends BaseAgiScript
{
public void service(AgiRequest request, AgiChannel
channel) throws AgiException
{
answer() // Answer
streamFile(quot;welcomequot;) // play file
hangup() //hangup
}
}

20. AMI Topology
Grails
Cell
Origination/
Phone
Termination
Server
PSTN
Asterisk
Internet
AMI
Web Request

21. Asterisk – Groovy AMI
import org.asteriskjava.manager.*
class HelloManager
{
def void run() throws IOException,
AuthenticationFailedException, TimeoutException
{
originateAction = new OriginateAction()
originateAction.setChannel(quot;SIP/Johnquot;)
originateAction.setContext(quot;defaultquot;)
originateAction.setExten(quot;1300quot;)
originateAction.setPriority(new Integer(1))
originateAction.setTimeout(new Integer(30000))
}

22. Asterisk - Java
Write Groovy in our
➢
dial plans!
Ability to use
➢
databases,
frameworks (Grails)
rd
and 3 party Java
libraries.
Test and debug our
➢
application in
isolation.

23. Asterisk - Java
It's Java (or Groovy)
➢
It's simpler
➢
It's extensible
➢
It's readable
➢
It's maintainable
➢
Bring OO practices to
➢
VoIP development.

24. Asterisk Screencast
Learn more at http://localtone.blogspot.com/
➢
Downloading Asterisk.
➢
Configuring Asterisk in extensions.conf
➢
Download X-Lite or SJ Phone.
➢
Register to Asterisk two phones using SIP
●
protocol.

25. Real World Application
eStara
Offers a service where a
user browsing a site
can enter their phone
number. The system
will dial their number,
ask the person to hold
and then dial customer
service.
We'll do this.

26. Amazon Support – Click to Call

27. Click to Call Web Service
Problem:
You have a website and want to allow your users
to type their phone number in and have your
business phone ring and then connect the call.
Web service allows you to pass in a source phone
number, a destination phone number and an API
Key.

28. Web Service Request
Request:
/dial/create?source=${SOURCE}&destination=${D
ESTINATION}&apiKey=${APIKEY}
Result:
<Result xml:ns=quot;urn:localtone:clicktocalljavaquot;
xsi:schemaLocation=quot;http://api.localtoneinteractiv
e.com/ClickToCallJava/V1/DialResponse.xsdquot;>
<Guid>IQ40M</Guid>
<Status>100</Status>
<Description>Call queued</Description>
</Result>

29. Web Service Status
Request: /clicktocalljava/dial/show/IQ40M
Result:
<Result xml:ns=quot;urn:localtone:clicktocalljavaquot;
xsi:schemaLocation=quot;http://api.localtoneinteractiv
e.com/ClickToCallJava/V1/DialResponse.xsdquot;>
<Guid>IQ40M</Guid>
<Status>200</Status>
<Description>No Answer</Description>
<Source>SIP/200</Source>
<Destination>SIP/200</Destination>
<User>admin</User>
</Result>

30. GitHub Project
Current code for the click to call web service
implemented in Asterisk-Java can be found at:
http://github.com/justingrammens/clicktocalljava/tr
ee/master
Working on an implementation in Ruby, using the
Adhearsion framework.

31. Questions?
Thanks!