Business in Thailand : Essential Services

:: Overseas call services by CAT Telecom Public Company Limited : For Home / Office

1. 001 Automatic Calling System

ISD 001

International Subscriber dialling (ISD) is an overseas telephone service which subscribers can operate by self-pressing the numbers to destination countries by dialling 001

 How to use

  • Dial 001 + Country code + Area code +Destination Number
  • 001= International access code
  • 1= The U.S.A. country code
  • 415= The area code where San Francisco belongs to
  • (For some countries, Area code is not applicable)

xxxxxx   = The destination telephone numbers. Wait for answering ringing tone for about 30 seconds. If you do not here the answering ringing tone after 30 seconds, hang up and start again.

Call Charges

The ISD Calls are in the first-minute duration charge category and then charges are calculated in blocks of 1 unit, (6 seconds.) ISD call charges are divided into three rates as fallows:-


Standard Rate

Economy Rates

Reduced Rates




7.00 am. 9.00 pm.

9.00 pm. 12.00 pm

12.00 pm. 5.00 am.

On Economy Rates

and Between


are applied instead

5.00 am. 7.00 am.


The calls that span from one rate to another rate will be charged at the rate the call starts.

Country Codes and Area Codes

* Country Codes and Area Codes are depicted in this folder.
* Generally, the majority of overseas numbers at hand start with Area Codes (particularly USA). If not included or you need assistance, please call operators. (dial 0-2950-3712 or 0-2614-1000)
* For some countries, The Area Codes are not required.

Hints on Making ISD Calls

* For all ISD Calls, Please allow up to 30 seconds for your call to go through after dialling.
* If a connection tone is not heard within approximately 30 seconds after dialling, hang up your phone and redial.

Some Advices for your Benefit

* Prepare what you want to say before dialling.
* Make sure that Country Code, Area Code and Called Party Number are correct.
* Make sure that you hang up your phone after the call.


* Dial 0-2614-1000 for area codes not listed in this folder or any other information required, for the ISD call.
** The ISD technical Information Centre contactable on Tel. 0-2950-3694-5

2. 100 Operator Assisted Call

Operator Assisted Call 100

Operator Assisted Calls are international call services where callers would reach CAT Telecom Plc.'s operators by pressing "100" and the operators Will connect callers to the desired destinations.

Three call types

  1. Station Call is placed to the requested telephone number no matter who picks up the phone
  2. Person Call is placed to the person requested at the desired telephone number
  3. Collect Call requests the recipient party to pay for the call. If affirmative, the call will be connected only if that party accepts the charges. This type of service is only available to countries that have this specific type of payment method with CAT

Call charges

Minimal chargeable duration is 3 minutes. After the first 3 Minutes, each minute is Charged, and the duration of the call is calculated on the whole number of minutes. One surcharge minute is added for a Person Call. One rate is applied for 24 hours.