Introduction

Many phone handsets are equipped with calling number display (“CND”), enabling the called party to see the number of the person calling before he/she answers the call.  The telephone number shown on the CND is, however, susceptible to be changed/falsified by scammers by means of “caller ID spoofing”.  According to the Police, there has been a surge in phone scams lately involving caller ID spoofing.  The Police indicates that these phone scams originate from outside Hong Kong.

 “+” Sign to Indicate Incoming Calls From Outside Hong Kong

To help detect caller ID spoofing, as from 21 August 2015, the telephone operators are required to insert a “+” sign in the CND of mobile phones as a prefix for all incoming calls originating from outside Hong Kong, even if, for instance, the calling number is masqueraded as a local Hong Kong phone number.  The “+” sign enables the public to identify from the CND the origination of the incoming calls is from outside Hong Kong.

Limitations about “+” Sign on the CND

The display of the “+” sign on the CND of a mobile phone for an incoming external call may be subject to the following limitations:

• If the bogus calling number matches with a phone number stored in the directory of the called party's mobile phone, the phone may display the name corresponding to that phone number rather than the calling number with the “+” sign; and

• While all the relevant telephone operators have endeavoured to implement the necessary measures in their networks, there may still exist some rare call scenarios¹ in which the “+” sign for incoming external call to the called party is not displayed.

The insertion of the “+” sign to all incoming calls originating from outside Hong Kong seeks but to alert the public to possible phone scams.  Whether or not the “+” sign is shown on the CND of mobile phones, members of the public are advised to always stay vigilant in regard to suspicious phone calls from dubious callers.  In order to avoid falling into the traps of fraudsters who are engaged in caller ID spoofing, you are advised to take the following precautionary measures:

Precautions against Caller ID Spoofing

• On receipt of calls with “+” sign on CND, or calls from strange or unknown/unfamiliar numbers, you should be alert to the possible fraudulent identity of the callers. Remember, you always have the option of not answering the call. If you decide to take the call, you should remain vigilant and be on guard against possible telephone scams throughout the telephone conversation;

• You should not disclose any personal information to or accede to any request of a dubious caller. If in doubts, always seek advice and help from family members or friends;

• For telephone calls received from parties purporting to be officials of local or overseas organisations, you should try to ascertain the identity of the calling party during the conversation;

• If in doubts, once the conversation is over, you should call directly the organisation that the caller purports to represent for verification of his/her identity, through telephone numbers/websites you identify from sources other than the calling party;

• Please alert your family members and friends, especially the elderly and youngsters, who are more vulnerable to frauds, to the surge in phone scams and advise them to take the precautionary measures and to stay vigilant to possible phone scams; and

• Report immediately to the Police about questionable calls received, and suspected phone scams.

Office of the Communications Authority

 ¹  For example, the “+” sign cannot be shown on the CND of certain very aged model phones (such as those which show digits only).