I now get:- /usr/src/asterisk/dsp.c:1395: undefined reference to `ast_dsp_busydetect' The Make file changes modify BUSYDETECT but if you have BUSYDETECT+= -DBUSYDETECT_COMPARE_TONE_AND_SILENCE the above error is shown. Renabling BUSYDETECT+= -DBUSYDETECT_MARTIN corrects the problem. -- Dave Cotton <dcotton@linuxautrement.com>