Hi,

> CAPI = ?

CAPI (Common Application Programming Interface) is an international
standard interface that applications can use to communicate directly
with ISDN equipment. Using CAPI, an application program can be written
to initiate and terminate phone calls in computers equipped for ISDN.
Computer telephony (CTI) applications can be written for ISDN users.
Officially, CAPI is referred to as Common-ISDN-API and is embodied in
ETS 300 838 ("Integrated Service Digital Network (SDN); Harmonized
Programmable Communication Interface (HPCI) for ISDN." ETS refers to
standards from the European Telecommunication Standards Institute
(ETSI). The standard is internationalized by recommendation T.200
"Programmable communication interface for terminal equipment connected
to ISDN" from the International Telecommunications Union (ITU).
CAPI can be compared with the Intel-Microsoft "standard" programming
interface, the Telephony Application Program Interface (TAPI). CAPI
includes signaling and data exchange protocols not included in TAPI.
TAPI services are also provided by CAPI and a TAPI application can be
mapped to CAPI functions.

Because ISDN is widely used in Germany, the Netherlands, and
Scandinavia, users there are accustomed to receiving a CAPI software
program or driver along with their ISDN computer card. Not all CAPI
driver versions support all functions. CAPI provides functions that are
independent from physical signaling protocols that vary among different
countries. CAPI supports these protocols: HDLC, HDLC inverted, SDLC,
LAPD, X.75, Voice (PCM), Fax group 3 (T.30), V.110/V.120, and
compression (V.xx).

> ignorant, but trying to learn,

ignorant but knowing whatis.techtarget.com

HTH
Andre