Privacy Commissioner Community advice

Who's calling? Your privacy and calling number display

• What is Calling Number Display?
• What are the privacy issues with CND?
• What can I do to stop my number from being sent?
• What legal protection exists for my information collected through CND?
• Where can I get more information?

What is Calling Number Display?

Calling Number Display (CND) is a telephone service which enables you to see the telephone number of the person who is calling you before you pick up the phone. To receive the service, you will need to subscribe and have a phone handset with a display capability.

CND also means that other people can identify your telephone number when you call. From the time it is introduced, your own number will automatically be transmitted down the line regardless of whether or not you subscribe to the service. This means that every time you make a phone call your number will be capable of being seen and retained by the person you are calling, unless you take particular action (see the section below on What can I do to stop my phone number from being sent to other people?).

It is argued that the service benefits consumers by giving increased control in handling incoming calls by allowing you to see who is calling before choosing whether to answer the phone. But this benefit is limited as the caller's number may not be displayed in every instance. For example, when someone is calling from overseas the message 'unavailable' is displayed. Likewise, the message 'payphone' will be displayed when the call is made from a public payphone. Also, for various reasons a caller may also choose not to send their number down the line. For example, they may have a silent number, they may have asked to have their line permanently blocked or, for quite legitimate reasons, they may simply not wish to send their number on that occasion. The message displayed on the screen in these circumstances is 'private'.

CND was introduced on 1 December 1997, initially on a trial basis in Adelaide. The service started throughout the rest of Australia on 15 December 1997.

Back to Top

What are the privacy issues with CND?

CND has the potential to significantly threaten your privacy when you are the person making the call.

An important aspect of protecting your privacy is your ability to control what you reveal about yourself, and when you reveal this personal information. Once CND is in place, each time you make a phone call, you will be sending your number automatically down the line to whomever you have called unless you take action to prevent this happening. But there may be certain situations when, for quite legitimate reasons, you may not want your number transmitted to the receiver, for example

• calling a counselling line;
• making initial enquiries with an organisation;
• calling a police phone-in line.

There are ways that you can exercise your choice about when you reveal your number. These are outlined below under Per call and permanent line blocking.

CND has a secondary aspect which threatens your privacy. The technology allows your number to be 'captured' or retained by the recipient of your call. Specifically, the CND display unit stores up to 40 telephone numbers of calls received and allows the recipient to retrieve those numbers if they wish.

More and more your telephone number is becoming a way of identifying you. It can easily be linked to other personal details an organisation may already hold about you, to increase the efficiency in handling your call. But it may also be linked to outside sources of information about you such as mailing list databases or reverse telephone directories. This information is of value to many businesses as a way of better targeting their customers. It is important that you are aware of the implications of allowing your number to be displayed and captured by those you call. The information may be used for other purposes than you intended, it may passed on to others without your knowledge and it may lead to more direct marketing and call backs from organisations.

It is important to bear in mind that the privacy implications of CND apply not only to the use of the phone in your home environment but also at work.

Back to Top

What can I do to stop my number from being sent?

There are a number of ways to stop your number being transmitted when you make a call. You can choose to block your number from your fixed telephone line on a per call basis by dialling 1831 immediately before you dial the number you wish to call. This prevents your number being displayed to the receiver of your call in that instance. Be aware though, that you will need to dial this number each time you do not want your number transmitted.

You can also arrange to have permanent line blocking on your phone. This means that your number will not be sent when you make calls. To do this you need to contact your telephone service provider and ask for a permanent line block on your phone. You can confirm that this block is in place by ringing 127 220. If there are occasions when you wish to send your number, you can override this block and send your number on a per call basis by dialling 1832 before you make the call.

The CND service has been configured so that if you have a silent number you will not have your number automatically sent to people that you call. This means that your line already has been permanently blocked. Again, you can unblock your phone on a per call basis. Should you have any queries about this aspect of CND, contact your service provider.

You can also choose to block your number when using a mobile telephone. You may be able to do this through the settings on your mobile telephone or you may need to contact your telephone service provider. You can block your mobile telephone number on a per call basis by dialling #31# before the number you wish to call. If you have set up a block and wish to send your number, dial *31# before the number you wish to call.

Back to Top

What legal protection exists for my information collected through CND?

There is limited legal protection for your personal details once they have been collected through CND. Commonwealth and ACT government agencies are legally bound to observe the Privacy Act in the way they collect, store, use and disclose personal information. These rules apply to personal information generated through CND technology. The Privacy Commissioner may investigate complaints about the way agencies handle personal information. If you think your personal details have been inappropriately handled by a Commonwealth agency, contact the Privacy Enquiries Line on 1300 363 992.

There are no laws binding businesses to observe privacy standards when they collect your information by using CND. Guidelines exist which provide standards of good privacy practice for businesses but these do not have the force of law. These guidelines were developed by the Austel Privacy Advisory Committee, the former telecommunications regulator.

Remember ...

Privacy principles hold that:

1. You should be able to choose when you want to reveal your personal information such as your telephone number, and
2. You should have some say in what is done with that information.

It is up to YOU to be aware about these aspects of the CND service which may pose a threat to your privacy:

• Your number will automatically be sent from the time the service is introduced. If you do not wish to have your number sent, you have to take action to stop it, either by per call blocking or permanent line blocking.
• If you do nothing, your number will be transmitted each time you make a phone call unless you have a silent number.
• Be aware of the implications of allowing your number to be displayed and captured by those you call.
• If you are making a call from someone else's phone you may be unwittingly disclosing their number to someone else. It may be wise to check whether they would like you to use the per call blocking service if they do not have a permanent line block in place.
• If you think your information is being handled inappropriately by a Commonwealth government agency, contact the Privacy Commissioner's office.

Back to Top

Where can I get more information?

For more information about the technical aspects of the CND service, contact your telephone service provider.

To check that line block is in place: 127 220

To block your fixed line number on a per call basis: 1831 before each call

To send your fixed line number if you already have a block in place: 1832 before each call

To block your mobile telephone number on a per call basis: #31# before each call

To send your mobile telephone number if you already have a block in place: *31# before each call

For further information please contact

Privacy Commissioner GPO Box 5218 Sydney NSW 1042

Privacy Enquiries Line: 1300 363 992 Fax: (02) 9284 9666

E-mail: privacy@privacy.gov.au

Back to Top