How to Lock STD/ISD facility in BSNL Landline Numbers.

For 100% protection against improper use, you can lock your telephone electronically. Here, you only know the secret code. You can lock/allow Local, STD or ISD calls in many way viz. all calls allowed, only local calls allowed, only STD & Local calls allowed, all outgoing calls barred etc. Register Secret Code Suppose you want to make 5555 your secret code. Follow this procedure to register  this: Dial 123 5555 5555 then wait for the acceptance tone then disconnect.  Your code is registered. Change secret code Suppose you want to change current code 5555 to 4444 then  Dial 123 5555 4444 then wait for the acceptance tone then disconnect.  Your new code(4444) is registered. Bar/Open Facilities using Secret Code(example 5555) Bar STD/ISD calls Dial 124 5555 1 then wait for the acceptance tone then disconnect.  Now STD/ISD calls will be barred . Open STD/ISD calls Dial 124 5555 0 then wait for the acceptance tone then disconnect.  Now STD/ISD calls can be made. Open STD calls only Dial 124 5555 3 then wait for the acceptance tone then disconnect.  Now STD calls can be made. Bar STD/ISD/manual trunck calls Dial 124 5555 2 then wait for the acceptance tone then disconnect.  Now STD/ISD/manual trunck calls will be barred .  (It will also bar calls to 95 level). Bar local calls Dial 124 5555 4 then wait for the acceptance tone then disconnect.  Now localcalls will be barred .(applicable only if STD Facility is available). Open local calls only Dial 124 5555 1 or 2 then wait for the acceptance tone then disconnect.  Now Local calls can be made.

later on, if anyone forgot the code then visit ur nearest BSNL exchange to get it reset again.