Although there have been sanctions against telecommunications operators involved in call masking, SIM-Boxing and related fraud, the menace still persists.
About this time last year, The Guardian exclusively brought the issue to light.
This spurred the Nigerian Communications Commission (NCC) to carry out some investigations, leading to the sanctioning and suspension of some operators earlier this year. Some of these suspensions were later lifted.
Lately, however, these menaces have reappeared, even more intensely, fuelling concern the country could be hit by a new wave of insecurity.
This has prompted experts and stakeholders in the sector to call for fresh measures to tackle the challenge.
Besides threat to security, especially in cyberspace, revenue meant for government coffers are also blocked.
A 10 per cent tax on all calls, telephony and telecommunications services goes to the government.
A masked call happens when an international calling number (Caller Line Identity) is masked as local number traffic.
It is a deliberate attempt by a fraudster to avoid paying the correct International Termination Rate (ITR) for international calls, paying instead the Local Termination Rate (LTR).
For example, when the number is masked as a local call, an operator pays N3.90 LTR and not N24.40 ITR.
The process allows operators to terminate inbound international telecoms traffic as local calls, so they don't have to pay ITR, which is the interconnection charge set by telecoms traffic carriers as carrier-to-carrier charges.
A SIM Box fraud is a setup where fraudsters install SIM boxes with multiple prepaid SIM cards.
The fraudster can bring calls through VOIP (through internet) and terminate international calls through local phone numbers in the respective country, to make it appear as a local call, by initiating the call through local SIM installed in the SIM box.
The Office of the National Security Adviser (ONSA), the National Intelligence Agency (NIA), the Department of State Services (DSS), and Committees of the House of Representatives and Senate have on several occasions expressed concern on the menace.
The Guardian learnt that as at March, call masking had cut the volume of international calls by 59 per cent. Industry analysts claimed this decline started from October 2016 when NCC jacked up ITR, which refers to the rate paid to local operators by international operators to terminate calls in Nigeria.
According to them, before NCC's intervention, the ITR was considered very low and was creating payment imbalance, as Nigerian operators paid the international operators in dollars to deliver international calls, a situation that worsened as the value of the naira plunged.
Speaking with The Guardian, the Director-General, Delta State Innovation Hub (DSHUB), Chris Uwaje, described the challenge as grievous, saying terrorists such as Boko Haram could explore it.
According to him, there is the need to ask why the menace was not there before and why it exists now.
Uwaje urged NCC to have an intrusion data mechanism that would help it to know the inlet and outlet of a call before the carrier executes its operation.
"They will sit as the man in the middle and be able to trace some of the acts. This is more of a data issue because calls are data-centric.
So, when a call is originated, it originates from 'free plus state of zeros and one', so you can match exactly, who is originating it, who the intermediary is and where it is going.
Having said that, it means we have reached a stage where NCC would have engineers with data algorithms experience, to be resident in each ISP data centre or where their headquarters are.
The security issue now is, if you want to trace a call to Boko Haram and they are using call masking to do that, automatically it becomes difficult to trace and any decision made from that move could be disastrous.
"Masking is to cover and it usually comes with intent. It is a crime. Why do you mask a number when automatically your caller ID is the one that will take precedence?
So, they are subverting the caller ID for several reasons, majorly economic, and that could lead to serious security threat for the country."
According to a Licenses Penetration Tester and Certified Ethical Hacker in Nigeria, Bolaji Arogun, call masking should be limited to security agencies alone, especially when they need to track someone perceived to have a committed a crime.
"Lately, it is becoming a new challenge as so many people are getting involved, mostly to commit fraud-related crime.
I think there should be urgent measures to stem its rising tide, especially among those people that are not security agents."
A telecoms expert, Kehinde Aluko, stressed that the menace of call masking and other vices were being fuelled by the huge difference between termination rates for local and international voice calls.
The development is therefore largely a ploy by perpetrators to illegally reduce their expenses while increasing their revenues.
"Decisive punitive action taken against one or two perpetrators would go a long way in serving as a deterrent.
Action in this regard could range from financial sanction to suspension, revocation of licence and prosecution for economic and financial sabotage, and perhaps even for threat to national security," he said.
Recall that in February, the NCC suspended three service providers and barred 750,000 lines for masking calls.
The 750,000 lines were numbers assigned to several Private Network Links (PNL) and Local Exchange Operator (LEO) licensees, whose number ranges were found to have been utilised for call masking in the past.
The NCC suspended the Interconnect Clearinghouse License issued to Medallion Communications Limited for a period of 90 days, in the first instance. However, the regulator, later in May, lifted the suspension.
The agency also disconnected two other companies, Information Connectivity Solutions Limited (ICSL) and Solid Interconnectivity Services Limited from all networks until they regularised their operations.
The fourth operator, Interconnect Clearinghouse Nigeria Limited, was lucky as it only got a strong warning from the NCC.
In the same vein, the NCC also issued letters of warning to Exchange Telecoms Limited, NiconnX Limited, and Breeze Micro Limited.
It cautioned them against engaging in the fraudulent practice.
Commenting on the issue, the President, National Association of Telecommunications Subscribers of Nigeria (NATCOMS), Chief Deolu Ogunbanjo, said there was no need to relent in reporting the menace to the right authority.
He said it could be a plan to ensure that gain accrued to some people. "I don't know whether call masking favours the operator or is being done deliberately.
If they are still in the habit of doing it, proper sanctions should be meted out to any erring service providers.
There should be heavier sanctions. They can't be short-changing subscribers and at the same time the government," he said.
A senior telecoms official in one of the leading MNOs told The Guardian, yesterday, that his firm, earlier this year, was exonerated in NCC investigations "that justify that this menace is not from us.
NCC should beam its searchlight properly on those earlier indicted. My network is not involved in such criminal activities."
He said the regulator should apply a more holistic approach since the menace has refused to go.
An official of an interconnect clearing house, which is still under suspension, said enquiries should be directed to NCC on why the menace remains despite all the sanctions meted out to the wrong people.
She said the commission knows what is ongoing on the matter, "and they know what should be done to stop the menace.
Even when they sanctioned some of us earlier in the year, the regulator knows those involved. They didn't do anything to them. Those ones have continued with the crime. Who is fooling whom in this country?
Those doing it are still very much involved. I am not surprised that the regulator has not been able to do anything. I don't see the menace stopping. But judgment would come one day."
Sources at the commission told The Guardian that NCC is setting up a three-digit code number, where those affected by call masking, SIM-Boxing, and other fraud cases could send the identified masked number for investigation.
It was revealed that there would be placement of paid announcements on radio and television with a short code to which subscribers could forward these numbers.
According to the sources, the new move is expected to reassure subscribers that something is being done to end the unsettling trend of international calls appearing with local numbers.
It will provide evidence for the security agencies that the commission has never been tolerant of the practice and perpetrators would be put on notice that the commission is set to take decisive action against the trend.
An official of one of the MNOs, who didn't want his name or office in print, said: "NCC intervention by way of sanctions imposed on culpable parties has reduced the incidence.
We shall continue to collaborate with the NCC, ONSA and the rest of the industry to mitigate the revenue and security impact of the issues."