Internet services will face partial disruption in the country for about 20 hours on October 31 and November 2 as the country's first submarine cable will remain partially disconnected for its upgradation.

The circuits through the South East Asia-Middle East-Western Europe 4 (SEA-ME-WE 4) submarine cable will remain partially disconnected for 10 hours from 2 am to 12 pm on October 31 and for another 10 hours from 2 am to 12 pm on November 2.

"We are increasing the capacity of the SEA-ME-WE 4 and when a system gets upgraded, the existing services need to be modified," Mirza Kamal Ahmed, managing director (additional charge) of Bangladesh Submarine Cables PLC (BSCPLC), told The Daily Star.

For that, the system needs to remain closed for a certain period, he said. The BSCPLC is spending $3.2 million to raise the capacity of its first undersea cable by nearly six times to 4,600 Gbps.

Currently, nearly 800 Gbps bandwidth is provided by the first undersea cable with which Bangladesh was connected in 2006. It has a capacity of 850 Gbps.

"Some of our customers' internet service will remain closed. But since SEA-ME-WE 5 will remain operational, the disruption will be partial," he added.

"It should be noted that the bandwidth capacity of the BSCPLC on SEA-ME-WE 4 submarine cable will increase significantly after the completion of the said upgradation work," the state-run company said in a statement.

The BSCPLC supplies 1,700 Gbps through the SEA-ME-WE 5, for which the connection was established in 2017.

Total bandwidth usage now stands at over 5,000 Gbps and more than half of it -- about 2,700 Gbps -- comes through international terrestrial cable (ITC) licences that import bandwidth from India across land borders.

The rest -- about 2,400 Gbps -- is supplied by the BSCPLC, which connects the country with two submarine cables.

The BSCPLC is set to receive 13,200 Gbps from a third undersea cable, SEA-ME-WE 6, by 2025.

The use of internet bandwidth is expected to shoot up by 600 percent in seven years to 30,000 Gbps as the government plans to connect all education institutions with the internet as part of establishing a blended education system -- integrating online educational materials with physical, location-based classroom techniques.

In September last year, private firms Summit Communications, CdNet Communications and Metacore Subcom Ltd obtained licences to establish, maintain and operate submarine cables in a development that broke the state monopoly in the wholesale bandwidth business.

The three have teamed up to connect the country with the first private submarine cable by 2025.