Appendix E
Playing sound files during an interview
Technical requirements. Playing sound files during an interview is accomplished via the telephone system. Using the Asterisk PBX system, CallWeb offers a way to easily start and stop playing such sound files. Sound files must be saved on .gsm format. Under Linux, several sound file editors can save files in this format. Under Windows, WavPad does it too.
Operations. Start playing a sound file by inserting a CALCUL question in the questionnaire and performing the following calculation: PLAY = start_wav("sound_file") where "sound_file" is the name of the file on the Asterisk server, typically custom/some_name without extension (since Asterisk will select the most relevant file format). The sound file will stop playing at the end of the file; it can be stopped using another CALCUL: STOP = stop_wav().
Installation. Assuming Asterisk is up and running, the rest of the installation required is as follows.