9.3.  Two-Way ADSI

• 9.3.1.  Transmit to On-Hook CPE
• 9.3.2.  Two-Way FSK
• 9.3.3.  Two-Way FSK for ADSI Functions

Two-way ADSI includes several enhancements to one-way ADSI, including the two-way Frequency Shift Keying (FSK). Two-way ADSI adds the following enhancements to the one-way ADSI capabilities:

• Transmit to On-Hook CPE (ADSI phones): Allows messages to be sent to an ADSI phone when the phone is either On-Hook or Off-Hook.
• Two-Way Frequency Shift Keying (FSK): Allows users to send and receive character or binary data at 1200 bits/second between the server and compatible devices, such as certain ADSI phones with keyboards. The two-way FSK feature supports applications such as off-line Email editing and sending FSK Caller ID data to a customer premise equipment (CPE) device through an MSI/SC board.

9.3.1.  Transmit to On-Hook CPE

The Transmit to On-Hook CPE feature supports the transmission of FSK data burst messages to CPE devices that are kept in the On-Hook state by either the CO or the PBX/KTS. This allows an ADSI/Caller ID phone to receive and potentially display messages while it is in the On-Hook state. For example, ADSI phones can be configured, accessed, and downloaded with features, outside of regular business hours while the phone is On-Hook, without ringing and without subscriber intervention.

NOTE:

The Transmit to On-Hook CPE feature works only if the CO supports this feature, or if an ADSI device is connected directly to a Dialogic MSI/SC board.

9.3.2.  Two-Way FSK

FSK (Frequency Shift Keying) is the modulation technique used to transfer data over voice lines. The basic ADSI capability supports only FSK Transmit (one-way FSK), in which an FSK message is sent from the Dialogic server to an ADSI display phone, with the phone in the Off-Hook state. The phone (CPE) sends dual tone multi-frequency (DTMF) messages to the server. As DTMF messages are sent to the server, the effective data rate is very slow, approximately 6 characters per second maximum. This speed is satisfactory for ACK/NAK signaling but it is not usable for any bulk data transport in the inbound direction from the CPE.

NOTE:

FSK data reception uses a DSP-based Bell 202/V.23 low speed (1200 baud) modem receiver. A 1200 baud modem does not need to train for data transmission, and therefore is faster than a high-speed modem for short data bursts.

Two-way FSK for ADSI supports the transmission and the reception of FSK data between the server and the CPE. The server initiates the reception of data from the CPE by sending a CAS to tell the CPE to switch to data mode, followed by a message that tells the CPE to switch to peripheral mode. Once it is in peripheral mode, the CPE can send FSK messages to the server using the ADSI Data Message Format (ADMF), instead of the slower DTMF-based scheme.

NOTES:

1. See Section 9.5.  Developing ADSI Applications for a more detailed description of how use the Dialogic library functions to develop two-way ADSI data transfer applications.

2. For more information about two-way FSK transmission, see the Bellcore Special Report SR-3462, A Two-Way Frequency Shift Keying Communication for the ADSI. Bellcore documents can be obtained from Bellcore by calling 1-800-521-CORE.

In addition to features provided by basic ADSI Two-way FSK for ADSI can be used in the following applications:

• sending and receiving Email between display-based ADSI phones and the server
• sending FSK Caller ID data through the MSI to a CPE device

NOTE:

To send Caller ID information through an MSI/SC board, the ADSI phones connected to the board must be able to detect and accept the transmission of Caller ID information prior to the first ring.

9.3.3.  Two-Way FSK for ADSI Functions

There are three Data Transfer functions included in the Voice Software Reference: Programmer's Guide that are used to support the two-way FSK feature . These functions are as follows:

• dx_TxIottData( ) - sends data
• dx_RxIottData( ) - receives data
• dx_TxRxIottData( ) - sends and then receives data

Section 9.5.  Developing ADSI Applications provides instructions for using these functions to develop one-way and two-way ADSI data transfer applications.

NOTE:

Users with older ADSI applications: The dx_play( ) function can still be used for the transmission of ADSI data. However, future enhancements to the ADSI feature and functionality will not be made to the dx_play( ) function. Therefore, we recommend that you convert your older ADSI applications and replace dx_play( ) with the new dx_TxIottData( ) function. See Section 9.5.3.  Modifying Older One-Way ADSI Applications for more information.

In addition, the following functions are used to support the two-way ADSI:

• dx_setparm( ) - sets board or channel parameters
• dx_getparm( ) - retrieves current parameter settings

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