To control improper use and controll telephone bill, you can lock your telephone electronically with the help of a secret code to be chosen by you. It's F-R-E-E

First Time Registration: Choose a 4- digit code. Dial 123 followed by the secret code twice. That is, ."123-xxxx-xxxx" (where the code  "x" may be any numeric no). Wait for an acceptance tone (busy tone with a long duration.) acknowledging the command and then disconnect. Please remember this code and keep it a secret.

Bar/Allow STD /ISD: Dial "124-xxxx-1" wait for the acceptance tone and
disconnect. Now STD/ISD facility is barred.Dial "124-xxxx-0". Wait for the acceptance tone and disconnect. Now the STD/ISD facility is available again..

Bar /Allow other Type of Calls: Similarly by dialing "2","3","4" after the secret code the subscriber can bar various types of calls on his telephone given below.

• Only local calls to be allowed and 95/STD/ISD calls to be barred. Dial "124-xxxx-2", wait for acceptance tone and disconnect.
• Only local calls, STD calls, Special Services calls to be allowed and ISD calls to be barred. Dial "124-xxxx-3", wait for acceptance tone and disconnect.
• Only Incoming calls to be allowed and all types of out going calls to be barred : dial "124-xxxx-4", wait for acceptance tone and disconnect. For reintroducing the barred facility: dial 124-xxxx-0.
   

You can change the 4-Digit secret code, if you want to. For this, the procedure is as follows:- Dial 123 followed by the present code followed by the newly chosen code. For example, if you want to change the code from "xxxx" to "abcd", dial "123-xxxx-abcd". Wait for the acceptance tone and then disconnect. Your code now be "abcd". In order to ensure security against unauthorized usage, the system will reject the command if the code used is incorrect. If incorrect code is used 9 times. The telephone is permanently locked on the last status. This can be reset only by the exchange in-charge.