Caller ID(CID) is a service provided by your telephone service, it allows using a special device or modem supports Caller ID, get the caller's number, and the date and time. The subscriber must contact the telephone company to request this service. Number identification system Caller ID is possible if the PBX callee and caller support CID. If the connection happens via transit PBX, then they must support this service. Room information received from the PBX caller to the called PBX while transmitting data on the connection request, then the PBX called subscriber gives it information about the calling number, the time and date during the 4-second pause between 1st and 2nd ring parcels. Caller ID sends the data in the binary system, bits are grouped together in the 8-bit bytes, each byte is limited to the initial and the final bits. Transmission is performed with the following parameters:
Data transfer rate............................. 1200 bits/sec Mark (logical 1)............................... 1200 (+/-12) Hz A space (logical 0).............................. 2200 (+/-22) Hz The send level with a resistance of 900 ohms................. 13.5 dBmThe data transmission Protocol:
1)the Signal channel capture - 30 continuous bytes of 55h (01010101). Is used to check the performance of this function in the determinant. 2)the Signal courier - 1200 Hz, 130 (+/-25) MS. Click to create the conditions to receive. 3)Information about the caller: 3.1)the Type of data - CID - 04h (00000100) 3.2)Byte indicates the length of information (total number of bytes) 3.3 to 3.7 3.3)Two bytes indicating the month in ASCII 3.4)Two bytes indicating the day of the month in ASCII 3.5)Two bytes indicating the hours local time in ASCII 3.6)Two bytes indicating the minute of the hour in ASCII 3.7)called Number in ASCII, if instead of the number: O - not specified P - the caller has imposed a ban on caller ID 3.8)Bytes indicating a checksum. Is used to check the correctness of the information received. With proper transmission and reception of 3.8 = summe bytes 3.1 to 3.7An example of reception of the information with Caller ID
Here is an example obtained from the exchange of information (paragraph 3).
The following data were obtained:
04 12 30 39 33 30 31 32 32 34 36 30 39 35 35 35 31 32 31 32 51 (Hex).
04h.......................................... the type of information - Caller ID (CID)
12h............................................ the number of bytes of the date, time, room 18
30h,39h (ASCII"09") ............................. the month - September
33h,30h (ASCII"30") ................................. day - 30th
31h 32h (ASCII"12") .................................. time - 12:xx
32h,34h (ASCII"24") ............................... min - xx:24
36h,30h,39h,35h,35h,35h,31h,
32h,31h,32h (ASCII"6095551212") .............. room 609 5551212
51h............................................................. the word Control semioperational rooms will display the following information: SEPT 30, 12:24 (609) 5551212.
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