122 Voice API Programming Guide — June 2005
Send and Receive FSK Data
acknowledge and the data transmission (and/or reception) will then be initiated. Once the data
transmission/reception is complete, the devices switch back to voice mode.
This newer implementation of ADSI is supported through the dx_RxIottData( ),
dx_TxIottData( ), and dx_TxRxIottData( ) functions. This implementation is referred to simply
as “ADSI Support” or “Two-Way ADSI.” This newer ADSI support provides for both one-way and
two-way ADSI transmission and is the recommended method for implementing either one-way or
two-way ADSI in an application program. The older one-way ADSI support can be used but is not
recommended. Future enhancements to ADSI feature and functionality will not be made to the
dx_play( ) and dx_playf() functio ns. See Section 10.9, “Modifying Older One-Way ADSI
Applications”, on page 133 for information on converting from the older to the newer method for
using ADSI.
10.2 ADSI Protocol
ADSI is a superset of the caller ID and call waiting functions. ADSI is built on the same protocol as
caller ID and shares the same ADSI Data Message Format (ADMF). The ADSI protocol requires a
Bell 202/V.23 1200 bps FSK-based modem for data transmission.
The ADSI protocol supports a variable display size on a display-based telephone. An ADSI
telephone can work in either voice mode or data mode. Voice mode is for normal telephone audio
communication, and data mode is for transmitting ADSI commands and controlling the telephone
display (voice is muted in data mode). An ADSI alert tone is used to verify that the hardware is
connected to an ADSI telephone and to alert the telephone that ADSI data will be transferred.
The ADSI protocol consists of three defined layers, as follows:
message assembly layer
assembles the body of the ADMF message
data link layer
generates the checksum, which is used for error detection, and sends it to the driver
physical layer
transports the composite message via the modem to the CPE on a transparent (bit-for-bit) basis
Intel provides only the physical layer and a portion of the data link layer of the ADSI protocol. The
user is responsible for creating the ADSI messages and the corresponding checksums.
The ADSI data must conform to interface requirements described in Telcordia Technologies
Generic Requirements GR-30-CORE (formerly TR-NWT-000030), Voiceband Data Transmission
Interface Generic Requirements. For information about message requirements (how the data
should be displayed on the CPE), see Generic Requirements GR-1273 (formerly TR-NWT-
001273), Generic Requirements for and SPCS to Customer Premises Equipment Data Interface for
Analog Display Services. To obtain a copy of these technical references, call 1-800-521-2673 (from
the U.S. and Canada) or +1-732-699-5800 (worldwide), or visit http://www.telcordia.com. Note
that Telcordia Technologies was formerly known as Bellcore.