Overview of Caller ID Standard and Market in Taiwan
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Overview of Caller ID Standard and Market in Taiwan
Market Status
In 1999, Chunghwa Telecom, the state owned telephone carrier in
Taiwan, had officially launched Caller ID service in Taiwan. By
offering Caller ID service as part of the standard telephone package,
Chunghwa Telecom is one of the first carriers to implement Caller ID
on an existing network without additional charges. Since Caller ID
features are traditionally considered a paid service, Chunghwa Telecom
is raising the standard for what is considered basic telephone
service.
Owing to the network compatibility issues, Type 1 Caller ID service
is being offered in certain cities or areas only with number delivery.
The incompatibility and limited service area leads to a problem of
usability. Often, calls from outside the various service areas are
reported as "Out Of Area". As a result, the performance of
the current Caller ID Service is below some customers’ expectation
and anticipation. The general feeling from various Caller ID device
manufacturers is that the limited service areas are reducing the
benefit of Caller ID and resulting in disappointed customers. As such,
the demand for Caller ID devices from consumers is slowing from the
initial surge.
Official Caller ID Standard
Taiwan has adopted both FSK and DTMF Caller ID transmission
formats as per the ETSI Standard ETS 300-659-1. Depending on the
capabilities of the central office switch serving a given area, the
Caller ID data is transmitted by means of a FSK modulated carrier or
by sending DTMF digits. The official Caller ID document 0003-0 was
released on Nov. 22, 1999 by the Directorate General of
Telecommunications, Republic Of China.
FSK Caller ID Transmission
The FSK based Caller ID transmission method uses a Dual Tone
Alerting Signal (DTAS) to inform the Terminal Equipment (TE) of an
incoming Caller ID message. The Caller ID message is sent using a V.23
FSK signal, which is followed by one or more power ringing cycles. The
following figure shows the sequence of events.
The timing limits are defined as follows:
|
|
Description |
Value |
|
T1 |
Silence time from DTAS to start of FSK data |
>=45 ms and <=500 ms |
|
T2 |
Delay from end of FSK data transmission to first ring |
>=200 ms and <=500 ms |
|
T3 |
Delay from the end of DTAS where the TE must be ready to
receive the FSK data |
=< 45 ms |
|
T4 |
Delay from the end of the FSK data where the TE must reject
further data |
=< 150 ms |
The Reason of Number Absence parameter type is slightly modified
from the ETSI specification. The following list shows the
representations used:
|
Reason of Number Absence |
Interpretation |
|
"C" |
Coin/Public Phone Call |
|
"I" |
International Call |
|
"O" |
Out of Area Call |
|
"P" |
Private Call |
DTMF Caller ID Transmission
The DTMF based Caller ID transmission method sends a series of DTMF
digits prior to the first ringing cycle. As shown in the following
figure, the calling number is sent following a "start" digit
and ends when the "stop" digit is detected.
The timing limits are defined as follows:
| |
Description |
Value |
|
T0 |
Pause for the central office switch to connect the DTMF
sender to the voice path |
50 ms ~ 400 ms |
|
T1 |
Duration of the DTMF digits |
>=50 ms |
|
T2 |
Inter-digit pause |
>=50 ms |
|
T3 |
Delay from the end of the last DTMF digit to the start of 1st
ringing cycle |
>=150 ms and <=700 ms |
|
T4 |
Time required to send all the DTMF digits |
=< 3000 ms |
|
T5 |
Return to quiescent state after receiving the DTMF stop digit
"C" |
=< 150 ms |
The transfer of number information is to be regarded as completed
when one of the following criteria are met:
1. The DTMF digit "C" (stop code) is received;
2. Ringing signal is detected;
3. After receipt of a DTMF digit the DTMF pause condition is
present for more than 1 second.
At least the criteria 2 and 3 shall be supported by the TE, as
these criteria will guarantee in both normal and abnormal number
information transfer procedures, that the NIT state is left before,
or as soon as possible, the line entering an off-hook loop
condition.
Caller ID Testing and Approval Authorities
Caller ID Terminal equipment are subject to formal approval
before they are permitted to be sold to the general public in
Taiwan. For further information, please contact the following
Official Approval Authorities:
ETC (Electronics Testing Center,Taiwan)
Tel : +886-3-328-0026
Fax: +886-3-328-3928
Contact: S.C. Chen
E-mail: johnson@etc.org.tw
TL (Telecommunication Laboratories Chunghwa Telecom Co., Ltd.)
Tel: +886-2-2326-2470
Fax: +886-3-424-5556
Contact: Jin Chuan Chan
E-mail: wxmc@ms7.hinet.net
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