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How to try out SEMS without setting up a proxy

Introduction

   This text describes how one can try out services in SEMS without
   setting up a proxy. This is the simplest way to try services in SEMS,
   or start with developing a service.

   The way this works is that SEMS registers to a SIP server (registrar)
   with one account (bob), just like any other SIP phone, and we call SEMS
   from another account (alice). If the SIP server provides DID calling
   from the PSTN, we can use any landline or mobile phone for testing or
   using the service.

   Note:
          What is not possible with this method is to use applications
          which need additional information for a call from the subscriber
          data. For example, in order to send a voicemail as email the
          SEMS server needs the email address to send the mail to.

Requirements

   For compiling SEMS, as a minimum a C++ compiler and make is needed. In
   debian, do
 apt-get install g++ make

With a public SIP server

   Two accounts at a public SIP server are needed. We recommend to use
   iptel.org's SIP service for testing, an account can be registered for
   free at [8]http://iptel.org/service/.

   Any SIP phone, hardphone or softphone, can be used for testing.
   Cross-platform, [9]sip-communicator is recommended, for Linux
   [10]twinkle, for Windows sip-communicator, xten eyebeam or NCH express.

With a PSTN DID provider

   Alternatively a PSTN DID provider can be used. In that case, we can
   test and use the service with any phone. A list of DID providers is for
   example available at [11]voip-info . [12]Sipgate for example, provides
   free DID numbers in Germany.

Installing SEMS from source

   First, the SEMS source is downloaded from iptel.org and extracted:
     $ wget ftp.iptel.org/pub/sems/sems-latest.tar.gz
     $ tar xzvf sems-latest.tar.gz

   SEMS is compiled:
    $ cd sems-x.y.z/
    $ make

   Note:
          Compilation may fail for some modules due to missing
          dependencies. For most modules, that can be ignored for the
          moment.

   Then SEMS is installed:
    $ make install

   This will install
     * configuration in /usr/local/etc/sems/
     * the sems binary in /usr/local/sbin/sems
     * modules in /usr/local/lib/sems/plug-in/
     * audio files in /usr/local/lib/sems/audio/

Configuring the application for SEMS

   There are many many modules shipped with SEMS, applications like
   announcement, voicemail, conference, etc, codec modules, and some
   things like SIP registrar client.

   Now we configure SEMS to load the conference application and execute
   the conference application for incoming calls. We also set it to have
   itself register to our SIP server.

   In /usr/local/etc/sems/sems.conf, we set
   load_plugins=wav;uac_auth;registrar_client;reg_agent;conference

   to load the modules we need; wav is for reading WAV files and for the
   G711 codec, uac_auth is the module which implements authentication,
   registrar_client facilitates registration at a SIP server, and
   reg_agent is the application that uses registrar_client to have SEMS
   register at a SIP server.

   We also set
   application=conference

   so that SEMS executes the conference application for an incoming call.

   We want SEMS to register at a SIP server, so we need to tell it about
   the user name and the password, this is set in
   /usr/local/etc/sems/reg_agent.conf (of course this user name bob and
   the password need to be set to the ones used for testing):
     domain=iptel.org
     user=bob
     display_name=bob
     auth_user=bob
     pwd=verysecret

Testing the setup

   Now we can test the configuration by running SEMS from the command line
   like this:
    /usr/local/sbin/sems -f /usr/local/etc/sems/sems.conf -D 3 -E

   -D 3 sets the debug level higher so that we see what is going on, and
   -E makes SEMS start in the foreground and go to daemon mode. It also
   makes the log appear on the terminal and not in the system log file.

   If everything is alright, SEMS starts up with a lot of messages, and
   hopefully no ERROR. There should also be some messages appearing which
   show that SEMS registered successfully to the SIP server.

   Now we can call bob from the other phone or our PSTN telephone. In the
   SEMS log, we see the call appearing, and on the phone we hear a message
   saying that we are the first participant in the conference.

   If it doesnt work.... we examine the log for the ERROR that occured.
   Possibly, depending on the network setup, we need to change the
   interface that SEMS is running on; this can be changed by setting the
   media_ip and sip_ip options in sems.conf. Also, it might be that there
   is already someone using that port (default config: 5070), in that case
   sip_port needs to be set.

Running as daemon

   If SEMS is started without the -E option, it will continue running as
   daemon in the background. The log can be seen in syslog (e.g. with tail
   -f /var/log/daemon.log).

Running other applications

   If we want to run other applications, the load_plugins= and
   application= parameters need to be adapted. See [13]Application Modules
   for a description of the shipped applications.

Creating and running a simple DSM applications

   The DSM is a service development platform, that makes it simple to
   create powerful services. The service logis is defined as a state
   machine, and the DSM application interprets this state machine for the
   calls, evaluating when to change state, and which actions to execute.

   To use a DSM application, we set in /usr/local/etc/sems/sems.conf
   load_plugins=wav;uac_auth;registrar_client;reg_agent;session_timer;dsm
   application=mydsmapp

   and in /usr/local/etc/sems/dsm.conf :
    diag_path=/usr/local/lib/sems/dsm/
    load_diags=mydsmapp
    register_apps=mydsmapp

   Then we paste this little script in
   /usr/local/lib/sems/dsm/mydsmapp.dsm :
  initial state BEGIN
   enter {
     playFile(/usr/local/lib/sems/audio/webconference/first_participant.wav);
   };
  transition "file ends" BEGIN - noAudioTest -> TYPING;

  state TYPING;
  transition "typed a key" TYPING - keyTest(#key < 10) / {
    set($myfile=/usr/local/lib/sems/audio/webconference/);
    append($myfile, #key);
    append($myfile, .wav);
    playFile($myfile);
  } -> TYPING;

  transition "BYE received" (BEGIN, TYPING) - hangup / stop(false) -> END;
  state END;

   This little script welcomes the caller, and then plays the key that the
   caller entered. More documentation about DSM and examples are in
   apps/dsm/doc, and also [14]DSM: State machine notation for VoIP
   applications .
     __________________________________________________________________


    Generated on Thu Feb 3 02:29:25 2011 for SEMS by  [15]doxygen 1.6.1

References

   1. file://localhost/home/stefan/devel/sems/sems/doc/doxygen_doc/html/index.html
   2. file://localhost/home/stefan/devel/sems/sems/doc/doxygen_doc/html/pages.html
   3. file://localhost/home/stefan/devel/sems/sems/doc/doxygen_doc/html/namespaces.html
   4. file://localhost/home/stefan/devel/sems/sems/doc/doxygen_doc/html/annotated.html
   5. file://localhost/home/stefan/devel/sems/sems/doc/doxygen_doc/html/files.html
   6. file://localhost/home/stefan/devel/sems/sems/doc/doxygen_doc/html/dirs.html
   7. file://localhost/home/stefan/devel/sems/sems/doc/doxygen_doc/html/examples.html
   8. http://iptel.org/service/
   9. http://www.sip-communicator.org/
  10. http://twinklephone.com/
  11. http://www.voip-info.org/wiki/view/DID+Service+Providers
  12. http://sipgate.de/
  13. file://localhost/home/stefan/devel/sems/sems/doc/doxygen_doc/html/AppDoc.html
  14. file://localhost/home/stefan/devel/sems/sems/doc/doxygen_doc/html/ModuleDoc_dsm.html
  15. http://www.doxygen.org/index.html