Breach of security of its ISDN installed at three corporate clients suspected

An international call scam, that appears to have breached the security of BSNL’s ISDN (Integrated Services Digital Network) networks installed in three companies, has left the operator clueless about recovering bill amounts running into several lakhs of rupees from its affected clients.

International calls of varying durations (from a couple of minutes to about half an hour), to destinations such as Somalia, Ethiopia, Poland, Guinea and Seychelles, were made from these firms during February, leading to generation of bills with a total value of over Rs. 60 lakh. The assumption is that an overseas operator stands to gain a windfall by way of call landing charges from such high volumes of inbound call traffic, a BSNL official said.

Ramco Systems, L&T Ramboll and a call-taxi operator are the affected ISDN clients of BSNL as they have run up bills in excess of Rs. 20 lakh. All these bills are now in dispute.

Prima facie, it appears that the ISDN facilities – fixed phone mini-exchanges with about 30 channels dedicated for voice and data – have been compromised, possibly by hackers, as such a huge volume of international calls is highly unlikely to be an inside job, the official said.

A spokesman for Ramco Systems said a police complaint was lodged at the cyber division of the Commissionerate last week though investigations were yet to commence.

BSNL Chennai Telephones spokesperson G. Vijaya said since the bills have been raised on metered calls; there is no waiver option of the amount. “However, as the affected parties are corporate clients, we have avoided disconnecting their lines altogether and provided some elbow room to come up with the payments,” she said.

BSNL has over 300 high-value corporate clients in Chennai alone. While BSNL believes that the ISDN systems of these clients were compromised because of lack of adequate firewalls or other system-safeguard software, a spokesman for Ramco System said their installations were well-protected.

Meanwhile, BSNL has issued advisories to its ISDN clients to ensure that their systems are firewall-protected. It is also keeping a tab on sudden surges in international call traffic. Though this time it is only BSNL’s ISDN networks that have been hit by the scam, there have been past instances where private networks too have taken a hit, industry sources said.

The prototype of a variant fraud in the mobile telephony segment takes the shape of a missed call, also known as the Wangiri , Japanese for one ring and cut. Unwitting subscribers call back to these international numbers which are often premium tariff lines and lose substantial money in the process.