SIM cards lie on Wednesday amid burnt articles outside the Baburbag Road house rented by Kausar. Picture by Munshi Muklesur Rahman

Calcutta, Oct. 10: The terror module in Burdwan’s Khagragarh had been using Bangladeshi SIM cards from areas close to the border to get in touch with counterparts in the neighbouring country to avoid coming under the radar of Indian agencies that track cross-border calls, investigators have learnt.

Sleuths said attempts to identify the Bangladeshi bosses of the Khagragarh module members of the Jamaat-ul-Mujahideen Bangladesh (JMB) in Bengal by tracing phone calls had drawn a blank because of the mode of communication.

The investigators came to know about the SIM card ploy by interrogating the two women arrested from the Khagragarh flat after the blast on October 2.

“JMB operatives in Bengal used to go near the Bangladesh border and use SIM cards of that country to make international calls. By doing so, they avoided routing the calls through the networks of Indian telecom companies. As they made the calls from near the border, they made use of telecom signals from a tower in Bangladesh,” an officer of a central intelligence agency in India said.

Interrogators said the two arrested women had told them that one of the module’s members would travel to the India-Bangladesh border to make phone calls to their bosses. The nearest border stretch from Khagragarh is in Nadia’s Meherpur, a distance of 150km that requires a three-hour road journey. Burdwan does not share a border with Bangladesh.

An official with an Indian telecom major said that because of geographical proximity, Bangladeshi cellphone networks could be accessed from areas in India that are close to the border by using SIM cards of companies of the neighbouring country.

In places other than border areas, an international call made using a Bangladeshi SIM card gets routed through the nearest telecom tower in India. Intelligence agencies usually monitor frequent callers to Bangladesh and Pakistan by tracking calls routed through telecom towers in India.

However, Indians sleuths cannot monitor towers in Bangladeshi territory.

“We have learnt that the JMB top brass had instructed members in India to use only Bangladeshi SIM cards. The move was planned after some of its operatives in Bengal came under the police’s scanner earlier this year while making international calls using Indian numbers,” a source said.

“The two women arrested from the Khagragarh flat after the blast have told the interrogators that Hamidul, a JMB operative in Bangladesh, had told them not to use Indian SIM cards to contact outfit leaders in that country,” the source added.

“But the problem is, we could not trace a single Bangladeshi SIM card as the two women, Gulshan Bibi and Alima Bibi, had destroyed them after the blast,” the source said.

“Had Indian intelligence agencies managed to seize the Bangladeshi SIM cards, they could have requested their counterparts in the neighbouring country to share the call records. That way, we could have got details on those behind the terror modules in Bengal,” the source said.

The five SIM cards the investigators found in the Khagragarh flat were of Indian telecom companies.

“The women told us that module members in Bengal had been instructed to use Indian SIM cards only while making inter-state calls. According to records, JMB operatives in Bengal had made calls to Jammu and Kashmir and Uttar Pradesh. Calls to Mumbai, Hyderabad and Chennai have also been traced,” a source said.

The Indian intelligence agencies are monitoring around two dozen phone numbers where regular calls used to be made using the five seized SIM cards.

Two arrests

The police today arrested two persons from Burdwan’s Ketugram for allegedly selling SIM cards against fake documents to people connected to the Khagragarh module.