Telecoms companies will have to invest in technology that automatically blocks scam calls originating from abroad but which pose as a local number. 

The Malta Communications Authority published the decision on Thursday, binding network operators in Malta to implement a series of changes to mitigate the spread of scam calls.

Deborah Pisani, senior manager of market operations at MCA, told Times of Malta the decision was largely aimed at tackling what is known as Calling Line Identification (CLI) spoofing: when a scammer makes it appear as though a call is coming from a trusted source such as a bank or post office.

These calls are often used as a vehicle to run a scam known as ‘vishing’, which is when the scammer attempts to trick those on the other end of the line into divulging sensitive and personal information that can be used to commit fraud or other crimes. 

Pisani said MCA was informed that the majority of scam calls received in Malta come from overseas, even when the number appeared to be of Maltese origin. 

The filters being proposed by the MCA will be able to pick up on some of the red flags of these illegitimate calls and automatically prevent them from reaching their intended target. 

“Since these calls are reaching Malta from abroad, we consider the local operators who receive traffic from foreign networks to be in the best place to implement these filters and provide a first line of defence,” she said. 

“In a nutshell, the filter will evaluate the calling and the called party numbers and decide on how that call will be handled.”

This can be achieved in a number of ways, but the filter can block out calls from numbers that contain a protocol that is currently invalid or not permitted. For example, in Malta, we do not currently make use of phone numbers that start with the digits 3, 5 or 6, so if a call does show up starting with those numbers, the filter will be able to block them. 

Deborah Pisani. Photo: Matthew Mirabelli

Another example is when calls come from a party that starts with the digit ‘2’ - the number associated with fixed lines in Malta and which are not typically received from overseas. Based on this, the filter will be able to block calls it screens as not being legitimate. 

The filters will, of course, make some exceptions to ensure that those who are making legitimate use of those protocols do not find themselves unexpectedly blocked. 

This includes the so-called inbound roamers - namely tourists in Malta who are using their foreign number to make calls to local numbers - as well as authorised cloud-based or over-the-top communications services, typically used by businesses and other organisations, that allow callers to make use of valid Maltese numbers when placing a call.

Where the latter is concerned, the MCA is going to require such providers to implement a subscriber validation process before allowing these kinds of calls. 

It is envisioned that telecoms providers will inform their customers of the implementation of these filters in June, with the MCA setting a deadline for the filters to be activated on November 1.