Some businesses use overseas call centres, many of which are located in India and the Philippines, because the labour costs in these countries are much lower.
Forum threads discussing +65 calls said they could also be from legitimate companies that use cloud-based Voice over Internet Protocol (VoIP) services to make voice calls using a broadband Internet connection instead of a regular phone line.
VoIP calls are cost-effective and can intentionally spoof a +65 number to make them appear more legitimate locally.
Mr Kevin Reed, chief information security officer at cybersecurity firm Acronis, said VoIP calls work using “from” and “to” entries.
“They resemble ‘from’ and ‘to’ on plain old letters – sender can write almost anything there and receiver may not even check the ‘from’ part because only ‘to’ is needed to actually deliver the (call),” he told CNA.
CallHippo, one such VoIP service, said on its website that its virtual Singapore phone number is affordable and creates “an illusion of local existence for your business”.
Restaurant reservation service Chope told CNA that calls from its automated reservation confirmation service come with the +65 prefix as it works with international calling services.
“Through this service, our restaurant partners can automatically get diners to confirm their upcoming online reservations without having to deploy staff to manually make those calls,” Chope’s head of operations Irving Tang said.
While Mr Tang acknowledged that some customers hang up on these calls, many restaurants still opt for these calls as they get a “very high response rate” from diners.
“We identify the purpose of the call quickly, plus do not ask for any personal information which could differentiate us from a typical scam call,” he said, adding that restaurants can opt for an SMS to be sent instead.
If diners do not pick up the +65 calls, Mr Tang said their reservations will remain, although restaurants can choose whether they keep these “unconfirmed” reservations.
“We are aware of the potential pitfalls of having the +65 prefix, and are currently exploring alternative ways to allow diners to confirm their reservations,” he added.
Citibank is another business that uses +65 calls, sometimes to offer additional banking services to clients in Singapore.
“Citi uses an international telephone numbering system that allows phone calls and text messages to be correctly routed to individual phones in different countries,” a spokesperson said.
“The security of our customers is highly important to us, thus we constantly review how we can improve the safety and effectiveness of our telephone services.”
BLOCK THEM ALL?
Despite some legitimate uses of +65 calls, Mr Reed said he would prefer such calls be blocked entirely and accept those from overseas call centres as “collateral damage”.
“I don’t think roaming users are really the problem, because they register at HLR (home location register) and thus can be distinguished,” he said, referring to the main database of permanent subscriber information for a mobile network.
Mr Reed said the introduction of the “+” prefix did not help much as scammers will always find a way to work around the “basic” solution, and have already done so in this case.
“It’s important to stress – this is a non-stop competition. Each side invents new ways to detect scams, while the other improves their scamming technique,” he said.
Telcos currently filter out and block suspected overseas scam calls by looking at what is called their signalling attributes, including where the calls come from and the numbers dialled, Mr Reed explained.