Returns "Yes" for carrier detect or modem in use and "No" otherwise.

V1.1 update: added command line options to select device name and unit number.

 PERMSSN    UID  GID    PACKED    SIZE  RATIO     CRC       STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                 1443    2823  51.1% -lh5- da99 Jun 12  1996 CheckCarrierV1.0.info
[generic]                  464     636  73.0% -lh5- 51b1 Jun 12  1996 CheckCarrierV1.0/checkcarrier
[generic]                  840    2086  40.3% -lh5- af89 Jun 12  1996 CheckCarrierV1.0/checkcarrier.c
[generic]                  440     790  55.7% -lh5- 2b1e Jun 12  1996 CheckCarrierV1.0/checkcarrier.doc
[generic]                   93     144  64.6% -lh5- 4d03 Jun 11  1996 CheckCarrierV1.0/SCOPTIONS
[generic]                  141     203  69.5% -lh5- 04ee Jun 12  1996 CheckCarrierV1.0/smakefile
[generic]                 1443    2823  51.1% -lh5- da99 Jun 12  1996 CheckCarrierV1.1.info
[generic]                  548     728  75.3% -lh5- 7513 Jul 24  1996 CheckCarrierV1.1/checkcarrier
[generic]                 1096    2674  41.0% -lh5- dc0c Jul 24  1996 CheckCarrierV1.1/checkcarrier.c
[generic]                  929    1820  51.0% -lh5- c9d0 Jul 24  1996 CheckCarrierV1.1/checkcarrier.doc
[generic]                   93     144  64.6% -lh5- 4d03 Jun 11  1996 CheckCarrierV1.1/SCOPTIONS
[generic]                  141     203  69.5% -lh5- 04ee Jun 12  1996 CheckCarrierV1.1/smakefile
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total        12 files    7671   15074  50.9%            Jul 24  1996