4.2. Northern Telecom SL-1

• 4.2.1. Northern Telecom SL-1 Switch Programming Requirements
• 4.2.2. Using the D/42D-SL Board
• 4.2.3. Feature Keys (8)
• Reading LED Line Indicators
• Example
• Pressing Feature Keys
• 4.2.4. Pressing Control Keys
• 4.2.5. Digit Display
• Example 1
• Calling Number ID
• Example 2
• 4.2.6. Setting the Message Waiting Indicator
• Example
• 4.2.7. Transfer a Call
• Example

The Northern Telecom SL-1 PBX use digital signaling to control its station sets and analog signals for voice. The D/42D-SL board has four channels that are connected directly to a SL-1 PBX. The SL-1 PBXs have many standard features that are supported by the D/42D-SL, such as:

• direct inward dialing (DID)
• hands free operation
• speed dialing
• hunt groups
• message waiting lamps
• call forwarding.

4.2.1. Northern Telecom SL-1 Switch Programming Requirements

Each port connected to a D/42D-SL must have the following Feature Keys assigned:

Feature Key 0	ACD or SCR - Automatic Call Distribution
Feature Key 1	TRN - Call Transfer
Feature Key 2	MIK - Message Indication
Feature Key 3	MCK - Message Cancellation
Feature Key 4	SCR - Single Call Ringing
Feature Key 5	User programmable
Feature Key 6	User programmable
Feature Key 7	User programmable
Feature Key 8	Handsfree
Feature Key 9	RLS - Release

There are no other specific PBX programming requirements for using a D/42D-SL with a Northern Telecom SL-1 PBX. However, you must ensure that the features you want to access using the D/42D-SL and the Unified API are enabled on the extension(s) connected to your system.

4.2.2. Using the D/42D-SL Board

The D/42D-SL board performs functions available to a Northern Telecom Digit Display telephone set (see Figure 12). A Digit Display telephone set uses LED indicators to show line status (next to the feature keys) and user information (above the keypad). The D/42D-SL can:

• transfer calls
• set the message waiting indicator
• read the LED display
• read LED line indicators
• read the calling number ID
• press buttons.

Figure 12. Northern Telecom Digit Display Telephone

4.2.3. Feature Keys (8)

There are eight Feature Keys located on the top-right of the Digit Display telephone - see Figure 12. These keys are configured when the PBX is programmed to any available station features. There is an LED Line Indicator associated with each Feature Key. Each Line Indicator can take on one the four states listed in Table 7.

NOTE:

There are no Line Indicators for Feature Key 8 (RLS) and Feature Key 9 (Hands Free).

Table 7. Digit Display Line Indicator States

Reading LED Line Indicators

The D/42D-SL can determine the state of its LED Line Indicators by using the d42_indicators( ) function to retrieve the Line Indicators data. This function places the Line Indicators data (8 bytes) in an application buffer. Each byte (8 bits) contains data representing one of the states listed in Table 7. Bytes 0-7 contain the indicator status for Feature Keys 0-7, respectively (see Table 8).

Table 8. SL-1 Dialing Strings for Feature Keys

Example

An application uses the d42_indicators( ) function to retrieve the current data for the LED Line Indicators on a given channel on a D/42D-SL. The data placed in the application buffer is shown below. If the data for byte 1 is 0x02, the LED Indicator for Feature Key 1 is flashing at 60 Hz. Refer to the D/42 Series Software Reference for your particular operating system for more information about using the d42_indicators( ) function

Pressing Feature Keys

The D/42D-SL can "press" any of its Feature Keys using the dial( ) function. Refer to the D/42 Series Software Reference for your particular operating system for more information about dialing programmable keys. Each Feature Key on the Digit Display telephone is assigned a dial string sequence (refer to Table 8). By using the dial( ) function and the appropriate dial string, the D/42D-SL can dial any Feature Key.

4.2.4. Pressing Control Keys

There are five control keys available on the Digit Display telephone.

Hold

Rls (Feature Key 9)

Handsfree (Feature Key 8)

Volume Up

Volume Down

There are no indicators associated with the control keys. The D/42D-SL can "press" any of its control key using the dial( ) function. Refer to the D/42 Series Software Reference for your particular operating system for more information about dialing programmable keys. Each control key on the Digit Display telephone is assigned a dial string sequence (refer to Table 9). By using the dial( ) function and the appropriate dial string, the D/42D-SL can press any control key.

Table 9. SL-1 Dialing Strings for Control Keys

4.2.5. Digit Display

The display is a 16-digit LED that is used to show:

• calling number ID (last 3 or 4 digits)
• trunk line ID
• date and time.

The data used to display information on the display is in ASCII format. The content of the display is updated automatically when receiving an incoming call. The D/42D-SL can retrieve the information on its display using the 42_display( ) function. The function places the display data (16 bytes) in an application buffer. Refer to the D/42 Series Software Reference for your particular operating system for more information about using the d42_display( ) function.

Example 1

An application uses the dial( ) function to press the appropriate Feature Key on a specified channel on a D/42D-SL to display the date and time. The 42_display( ) function is then used to retrieve the display data to read the date and time. The Digit Display data is shown below.

byte

data

byte

NOTE:

The format of the date and time may vary depending on the PBX and the PBX configuration.

Calling Number ID

When receiving a call on a D/42D-SL, the calling number ID (the extension of the telephone placing the call) is shown on the display and can be retrieved using the d42_gtcallid( ) function. The calling number ID data retrieved using this function is the same data that is sent to the display. Refer to the D/42 Series Software Reference for your particular operating system for more information about using d42_gtcallid( ) function.

NOTE:

On some manufacture's PBXs, the calling number ID data used for the display is not the same as the calling number ID data sent from the PBX to the phone set.

The calling number ID can also be obtained using the d42_display( ) function, however, you should use the d42_gtcallid( ) function so that your application will maintain functionality across different manufacturers' switches.




Example 2

An application uses d42_gtcallid( ) to retrieve the calling number ID for an incoming call received on a specified channel on a D/42D-SL. The calling number ID data and corresponding ASCII values are shown below.

data

byte

text

data

byte

4.2.6. Setting the Message Waiting Indicator

The D/42D-SL can set the Message Waiting Indicator (LED associated with Feature Key 2) of any extension using the dial( ) function and an appropriate dial string. Refer to the D/42 Series Software Reference for your particular operating system for more information about dialing programmable keys.

The D/42D-SL can determine the state of its Message Waiting Indicator using the d42_indicators( ) function to retrieve the LED Line Indicator data. Byte 2 corresponds to the LED indicator associated with the Feature Key 2 (Message indication) and is either off (0x00), on (0x03), or flashing (0x01 or 0x02). Refer to the D/42 Series Software Reference for your particular operating system for more information about using the d42_indicators( ) function.

Example

An application uses the d42_indicators( ) function to retrieve the Line Indicator data for a specified channel on the D/42D-SL to check if the Feature Key 2 LED is flashing. The Line Indicator data is shown below.

4.2.7. Transfer a Call

The D/42D-SL can transfer calls using the dial( ) function. By using the dial( ) function and the appropriate dial string (&,<extension>), the D/42D-SL can transfer a call to any extension connected to the switch. Refer to the D/42 Series Software Reference for your particular operating system for more information about dialing programmable keys.

NOTE:

The transfer function can be performed using the dial( ) function and the appropriate dial string to press Feature Key 1, however, you should use the &,<extension> dial string so your application will maintain functionality across different manufacturers' switches.

The D/42D-SL can perform both supervised and blind transfers (refer to Sections 2.1. Supervised Call Transfer and 2.2. Blind Call Transfer). When a blind transfer is performed, the PBX controls where the call is routed if the called extension is busy or does not answer. When a supervised transfer is performed, your application can implement call progress analysis and called/calling number ID to intelligently control where the call is routed and what type of message is played if the called extension is busy or does not answer. Because of this capability, supervised transfer is the preferred method.

Example

An application answers a call and plays a greeting message prompting the caller to enter the extension they wish to reach (the caller enters 221). Using the dial( ) function with the dial string (&,221), the application attempts to transfer (supervised) the call to extension 221. Call progress analysis is used to determine if extension 221 is answered, busy, or there is no answer. If extension 221 answers, the application hangs up and the transfer is complete. If the extension is busy or not answered, the application reconnects to the incoming call and plays a message asking the caller to choose between accessing voice mail or transferring to the operator.

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