September 2008
Intermediate to advanced
550 pages
18h 10m
English
Content preview from VoIP Voice and Fax Signal ProcessingBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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8.1 FSK CALLER ID ON PSTN
The popular methods for sending Type-1 FSK caller ID information are as follows:
- Data transmission between first ring and second ring
- Data transmission after alert but before actual first ring
- Data transmission after an OSI
All these implementations use the same basic data transmission sequence with minor variations in FSK generation among ETSI and Telcordia implementations.
Figure 8.1. FSK Caller ID between two rings. [Courtesy: Figure printed from ETSI 300 659-1 V1.3.1 (2001-01). “© European Telecommunications Standards Institute 2001. Further use, modification, redistribution is strictly prohibited. ETSI standards are available from http://pda.etsi.org/pda/”.]
Case-1 Data Transmission Between First Ring and Second Ring. It is commonly used in several countries such as North America, Canada, and so on. In this signaling method, FSK modulated data are sent during the silence periods between the first and the second ring. This on-hook service provides both number and name or only name as caller ID. The ring pattern is called cadence and varies with the country requirements. Data transmission shall occur during the first long silent period between ringing patterns as shown in Fig. 8.1. The first long silent period shall be of sufficient duration for transmitting FSK data. The initial application of the ringing provides an alert signal to the TE (phone) ...
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