Manual browser: isdntelctl(8)

ISDNTELCTL(8) System Manager's Manual ISDNTELCTL(8)


isdntelctlcontrol isdn4bsd telephone sound format conversion


isdntelctl [-c] [-g] [-u unit] [-A] [-U] [-N]


isdntelctl is part of the isdn4bsd package and is used to configure the sound format conversion facilities of the /dev/isdntel interfaces.

The following options are available:

Clear the telephone input queue.
Get the sound format currently in use.
Set the /dev/isdntel unit number. The default value is zero to access device /dev/isdntel0.
Do A-law (ISDN line) -> mu-law (userland) conversion.
Do mu-law (ISDN line) -> A-law (userland) conversion.
Set sound conversion to do no format conversion.

The telephony data stream comes out of the line in a bit-reversed format, so the isdntel(4) driver does the bit-reversion process in any case.

Additionally, the user can specify to do A-law to mu-law, mu-law to A-law or no conversion at all in the isdntel driver by using the isdntelctl utility.




The command

isdntelctl -g

displays the currently used sound format for device /dev/isdntel0.


A-law and mu-law are specified in ITU Recommendation G.711.


The isdntelctl utility and this man page were written by Hellmuth Michaelis <>.
April 21, 1999 NetBSD 7.0