Ericsson LBI-39076B Ending the Call, Radio-Originated Call, Obtaining a Working Channel

LBI-39076B OPERATION

PCM Data Bus (completing the audio path between the calling telephone and the called radio(s)).

28.The Site Controller directs the line-connected GTI to look for DTMF digits.

ENDING THE CALL

29.To end the telephone interconnect call, the caller presses the # key on the DTMF keypad and hangs up. (If the telephone does not have a # key, the caller can just hang up.)

30.When the line-connected GTI detects the DTMF # digit (or end of call signaling, if the line provides it), it gets a message to the Site Controller indicating that the telephone has been hung up.

The called radio user can also terminate the call by pushing the EXIT, SPC, or designated button on the radio (see the operator's manual for the radio). This causes the radio to transmit a disconnect signal to the assigned working channel GETC, and the GETC to send a message to the Site Controller.

31.When the Site Controller receives a hang up message from the line-connected GTI, a disconnect message from the Working Channel GETC, or the Transmission Conv Limit is exceeded (see System Manager screen 10, panel 2.), the Site Controller first directs the channel-connected GTI to extract itself from the audio loop of the assigned Working Channel, then directs the line-connected GTI to hang-up the line, and finally directs the assigned Working Channel GETC to terminate the call.

Radio-Originated Call

A request for a telephone interconnect call can be made from any radio that is equipped with the controls to place a telephone interconnect call. However, a telephone line will not be connected and the trapped telephone interconnect digits will not be re-dialed to the telephone line until the Site Controller computer has verified the following:

∙The trapped telephone interconnect digits meet the toll call restrictions for that radio ID.

∙The Site Controller computer receives the digital stream terminator digit.

∙All other system parameter and protocol requirements are met along the way (i.e., calling radio is valid for the site).

A telephone interconnect number is a string of decimal numbers (digits). The string can be anywhere from 0 to 32 digits long. It can be pre-programmed (pre-stored), or manually keyed just prior to pressing the PTT switch

(temporarily-stored). The radio automatically adds a terminator digit to the end of a pre-stored telephone interconnect number. However, you may have to manually add the terminator digit (press the * Key) at the end of a temporarily-stored telephone interconnect number (see operator’s manual for the radio). When a working channel is assigned, all digits including the terminator digit are sent digitally to the assigned working channel GETC. The channel-connected GTI takes the digitally-transmitted digits and decodes them for the Site Controller.

A telephone interconnect number may be a complete or partial telephone number. (An example of a partial telephone number is an access code plus an area code.) When the telephone interconnect number is only a partial telephone number, the caller must supply the remaining digits of the telephone number as overdialed digits, after the telephone line has been connected and the trapped interconnect digits have been re-dialed on the telephone line. Overdialed digits are logged by the Site Controller and then passed directly to the telephone line, through the channel- connected GTI and line-connected GTI, without interception and regeneration.

The toll call restrictions test is performed on the first 4 interconnect digits, or as many of the first 4 interconnect digits as it has received before receiving the terminator digit. The lack of the terminator digit will not hold up the toll call restrictions test once 4 interconnect digits are received, but the terminator digit must be received before the telephone line is connected and the trapped interconnect digits are re- dialed to the telephone line. If less than 4 interconnect digits have been received by the time the terminator digit is received, the Site Controller adds wild-card digits to the end of the string of received interconnect digits, until it has 4 digits for the toll call restrictions test. Each wild-card digit is tested for all possible values from 0 to 9.

The following sequence of steps describes the main events involved in a radio-initiated local telephone interconnect call:

OBTAINING A WORKING CHANNEL

1.The radio user sets the radio to the mode of operation that allows an interconnect call, selects a pre-stored telephone number or types in a temporarily-stored telephone number, and pushes the PTT switch.

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