9.1 Physical Description
The 9-1-1 PBX uses two asynchronous ports to send call tracking information to the ALI computers. The information is sent on both links at the same time without any protocol.
The 9-1-1 PBX is used to dispatch 9-1-1 calls to the answering attendants. It transmits call detail record information on its two RS-232 ports that enables the ALI system to identify which position is handling the 9-1-1 call at any moment. The CDR Message Types are defined in Section 9.4.3. The call detail record structure is defined in Section 9.5.
The same call detail record information is sent without protocol over both RS-232 ports simultaneously. The information is not checked for accuracy nor can a particular information set be retransmitted. The call detail record information for either a response or a transfer includes the following:
o the incoming trunk number of the 9-1-1 PBX (route and member) o the answering agent's line number (Terminal Number)
Because the emergency attendants' telephones are on ACD (Automatic Call Distributor), the DN (Directory Number) is not enough to identify them. The only way to identify the attendant is through his TN (Terminal Number). To simplify the message sent to the ALI, the TN is coded in 16 bits according to a specific format, thereby forming a hexadecimal number (HEX format).
9.2 9-1-1 PBX Sending a Message
Every time an emergency call is answered by a 9-1-1 agent working on the PBX, a message must be sent to the ALI computer to allow the display on the correct 9-1-1 terminal. A PBX message is transmitted indicating:
o New incoming call
o Conferencing party answered o Transferred-to party answered o Two-party call ended
o Transferred / conference call ended o Call ended
9.3 Data Link Management
The ALI - 9-1-1 PBX protocol always uses two data links without any handshaking protocol. This means that the 9-1-1 PBX dumps all the call tracking information on both data links at the same time. If one link fails, the ALI still receives the information on the remaining link.
9.4 Communication Protocol 9.4.1 Transmission Format
The PBX system transmits the following sequence:
nnnnnnMsp###spCCspTTTTnTTTspXXXXXXXspspspspspspspspspspspspspMM/DDspHH:MM spDD:DD:DDspcrlfnnnnnncrlf
Lower case characters are fixed.
Note: The Null (n) characters are not mandatory. They can be included in the message or not.
Capital characters are variable and used for:
M (Message type)
### (PBX Transmission Number)
CC (Customer ID)
TTTT TTT (Origin Number)
XXXXXXX (Termination or Directory Number)
MM/DD (PBX date)
HH:MM (PBX time)
DD:DD:DD (Call timer)
9.4.2 Control Characters
Table 21 - PBX protocol control characters Character Meaning ASCII Code
n Null 0 (00h)
cr Carriage Return 13 (0Dh)
lf Line Feed 10 (0Ah)
sp Blank Character 32 (20h)
9.4.3 Message Type (M)
The message type indicates whether the message contains beginning of call information, transfer information or end of call information. There are five different message types: Q This record is generated when a new call is answered by a 9-1-1 agent. It
F This record is generated when an attempt at conferencing a call is made. It indicates that the added on party has answered.
R This record is generated when an attempt at transferring a call is made. It indicates that the transferred-to party has answered.
N This record is generated at the end of a call which only involved two parties (e.g., subscriber on a 9-1-1 trunk and 9-1-1 agent). It is also generated on calls routed to the recorded announcement prior to being answered by a 9-1-1 agent.
E This record is generated when a call in the PBX is terminated. It is generated when a call involving more than one talk path (i.e., conference/transfer) was established.
9.4.4 PBX Transmission Number (###)
The transmission number is a tag attached to every transmission sequence; it helps keep track of the messages being sent. Its range is from 000 to 127. The transmission number is increased by one for each transmission and rolled over back to 000 when it reaches 128.
9.4.5 Customer ID (CC)
The Customer ID is used to identify a given 9-1-1 customer when the PBX is shared between several customers. Usually this field is 00.
9.4.6 Origin Number (TTTTnTTT)
A seven character segment containing calling party identification information. The Origin Number is represented as being one of the following:
Trrrmmm represents Trunk number where rrr is the route number and mmm is the member number.
DNxxxx represents Directory Number.
ATTNxx represents Attendant Number where xx is the console number.
CFlllnn represents Conference Number where lll is the loop number and nn is the conference number.
9.4.7 Termination or Directory Number (XXXXXXX)
A seven character segment containing terminating party identification. This field is represented as described in the previous paragraph.
Connection records (Q) are identified in the form TNxxxx, where xxxx is the loop, shelf, card and unit in packed format.
9.4.8 PBX Date (MM/DD)
A four character segment indicating the date as generated by the PBX. The date is represented as MM for Month and DD for Day.
9.4.9 PBX Time (HH:MM)
A four character segment indicating the time as generated by the PBX. The time is represented as HH for Hours and MM for Minutes.
9.4.10 Call Timer (HH:MM:SS)
A six character segment indicating the duration of a call. The duration is represented as HH for Hours, MM for Minutes and SS for Seconds.