[LAU] Service/user not using PulseAudio

Hi, Another Asterisk PBX related question. I have the Asterisk service periodically sending System commands on the host machine when particular phone extensions are called. The Asterisk service is run by the user asterisk. I made asterisk a member of the 'audio' group so that it can use 'aplay' with the System command. eg. System(aplay -c 1 -D pulse /home/iain/sounds/line1.wav) This plays OK but plays on the laptop's internal hardware rather via PulseAudio. Jack is running and is configured to use an external USB sound card and the PulseAudio Jack Sink. If I run the following as user iain, it plays correctly through the USB: aplay -c 1 -D pulse /home/iain/sounds/line1.wav However via the Aterisk service, or by running the command in a console as asterisk, it plays through the internal speakers. eg. sudo -H -u asterisk bash -c 'aplay -c 1 -D pulse /home/iain/sounds/line1.wav' I don't know if the "-D pulse" option is necessary, I'm trying lots of things... As well as the audio group, I've tried adding asterisk to the pulse and pulse-access groups, but it doesn't help (and yes, I logged out and in again). If i run the last code given above with aplay in verbose mode (-vvv), it throws the error: xcb_connection_has_error() returned true But this Is not error because adding "unset DISPLAY ; " to the start of the command removes the error but it continues to play through the external speakers. Here is the print for the command: iain@samsung:~$ sudo -H -u asterisk bash -c 'unset DISPLAY ; aplay -vvvv -c 1 -D pulse /home/iain/sounds/line1.wav' Tocando WAVE '/home/iain/sounds/line1.wav' : Signed 16 bit Little Endian, Taxa 48000 Hz, Mono ALSA <-> PulseAudio PCM I/O Plugin Its setup is:   stream       : PLAYBACK   access       : RW_INTERLEAVED   format       : S16_LE   subformat    : STD   channels     : 1   rate         : 48000   exact rate   : 48000 (48000/1)   msbits       : 16   buffer_size  : 24000   period_size  : 6000   period_time  : 125000   tstamp_mode  : NONE   tstamp_type  : GETTIMEOFDAY   period_step  : 1   avail_min    : 6000   period_event : 0   start_threshold  : 24000   stop_threshold   : 24000   silence_threshold: 0   silence_size : 0   boundary     : 6755399441055744000 iain@samsung:~$ Any suggestions please? Thanks, Iain