ISDN_USAGE_VOICE  222 include/linux/isdn.h #define USG_VOICE(x)        ((x & ISDN_USAGE_MASK)==ISDN_USAGE_VOICE)
ISDN_USAGE_VOICE  227 include/linux/isdn.h                              ((x & ISDN_USAGE_MASK)==ISDN_USAGE_VOICE)     )