VoIP Voice and Fax Signal Processing

8.4 COUNTRY-SPECIFIC CALLER ID OVERVIEW

Caller ID standards for data transmission and signaling have been published by various international standards committees, regulatory agencies, and network carriers, and they fall into one of two different categories based on how caller ID data is transmitted. They are FSK modulation or DTMF. The main deviations for multiple countries are on network transmission interfaces (power level, impedances) and timing variations for each country. These deviations will be available in country-specific PSTN standards. The Telcordia recommendation is used in the United States, Canada, Australia, China, Hong Kong, New Zealand, and Singapore, among others [URL (CID-FAQ)] with different data formats and with some deviations in signal characteristics. In on-hook caller ID, data are sent after the first ring tone is used. This scheme uses a 1200 baud rate for data and uses Bell-202 for FSK modulations. The data may be sent in SDMF, which includes the date, time, and number, or as MDMF that adds a NAME field. The most common and default method used is MDMF.

BT and CCA recommendations are used in the United Kingdom. British Telecom [BT SIN 227 (2004)] developed a different recommendation, which uses FSK modulations for data transmission based on the ETSI specifications.

DTMF-based [(URL (Cisco-CID)] caller ID is used in Brazil, Belgium, Denmark, Holland, Finland, Iceland, India, the Netherlands, Saudi Arabia, Sweden, and Uruguay. These are based on ETSI recommendations ...