Showing results for 
Search instead for 
Did you mean: 
Marcos Hernandez
For caller ID to work properly, IOS uses an internal setting based on the CPtone that is configured against the voice port, for example:

voice-port 0/1/0
cptone BE

Cisco supports:

* Telcordia Caller-ID support in North America Australia, China, Hong Kong,  and Singapore,
Telcordia Technologies (formerly Bellcore) - based on the GR-30-CORE specification.

* European Telecommunication Standards Institute (ETSI) Caller-ID support in France,
Germany, Norway, Italy, Spain, South Africa, Turkey, and UK (CCA), - based on the European
Telecommunication Standard ETS 300 648, ETS 300 659-1

* ETSI Caller-ID support in UK (British Telecom) - based on the British Telecom SIN227, SIN242

* NT FSK Caller-ID support in Japan - based on the Nippon Telegraph & Telephone Corporation standard

* DTMF-based Caller-ID support in Brazil, Belgium, Sweden, Denmark, Holland,
Iceland, and Saudi Arabia - based on the ETS 300 648, ETS 300 659-1


The format for Bellcore Caller ID is as follows -

To receive CND information, the voice port monitors the phone line between
the first and second ring bursts without causing the voice port to go off
hook in the conventional sense, which would inhibit the transmission of CND
by the local central office.  The CLID is sent as a burst of FSK modem tones
using 1200 baud Bell 202 tone modulation. The data may be sent in Single
Data Message Format (SDMF) which includes the date, time and number or in
Multiple Data Message Format (MDMF) which adds a NAME field. The CLID data
is based on the following format -


The channel seizure is 30 continuous bytes of 55h (01010101) providing a
detectable alternating function to the CPE


The carrier signal consists of 130 +/- 25 mS of mark (1200 Hz) to condition
the receiver for data.

The message type word indicates the service and capability associated with
the data message.  The message type word for CND is 04h (00000100).

The message length word specifies the total number of data words to follow.

The data words are encoded in ASCII and represent the following information:

The first two words represent the month
The next two words represent the day of the month
The next two words represent the hour in local military time
The next two words represent the minute after the hour
The calling party's directory number is represented by the remaining
words in the data word field

If the calling party's directory number is not available to the terminating
central office, the data word field contains an ASCII "O".  If the calling
party invokes the privacy capability, the data word field contains an ASCII

The Checksum Word contains the twos complement of the modulo 256 sum of the
other words in the data message (i.e., message type, message length, and
data words).  The receiving equipment may
calculate the modulo 256 sum of the received words and add this sum to the
reveived checksum word.  A result of zero generally indicates that the
message was correctly received.  Message
retransmission is not supported.


An example of a received CND message, beginning with the message type word,

04 12 30 39 33 30 31 32 32 34 36 30 39 35 35 35 31 32 31 32 51

04h= Calling number delivery information code (message type word)
12h= 18 decimal; Number of data words (date,time, and directory
number words)
ASCII 30,39= 09; September
ASCII 33,30= 30; 30th day
ASCII 31,32= 12; 12:00 PM
ASCII 32,34= 24; 24 minutes (i.e., 12:24 PM)
ASCII 36,30,39,35,35,35,31,32,31,32= (609) 555-1212; calling Party's
directory number
51h= Checksum Word
Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: