Netopia Router PN Series - Manual (Page 257)

ISDN Configuration Guide C-5
The table below shows which supported switch types can allow an
incoming call when ACO for data is on.
* Must have two directory numbers assigned.
This table may not be a complete list of switch protocols that
support ACO. To find out if your switch protocol supports ACO, or to
turn ACO on, contact your ISDN service provider.
Other incoming call restrictions
A B-channel will not be relinquished to admit an incoming call if a
connection profile has B-Channel Usage set to 2 B-Channels.
A B-channel will not be relinquished to admit an incoming call when
there are two separate concurrent calls. Incoming calls are
automatically allowed in when there is at least one B-channel free.
Type of switch: Incoming call allowed?
AT&T 5ESS custom N/A
AT&T 5ESS National ISDN-1 Yes
DMS-100 custom Yes*
DMS-100 National ISDN-1 Yes*