According to Bangladesh Telephone and Telegraph Board (BTTB) sources, only 80,000 telephones out of a total of 4,61,000 lines in the city are equipped with the system which accounts for only 17 percent of the subscribers.

Taking advantage of the absence of caller ID mechanism, miscreants have found it easier to terrorise and threaten people.

The tendency has increased over the last few years with extortion attempts and bomb threats becoming common menaces.

"We had received a phone in which the caller threatened to blow our school off with grenades just a few days after the grenade attack on Sheikh Hasina's rally on August 22," said a senior teacher of a reputed English medium school in Dhanmondi.

Other academic institutions including the Dhaka University, also received such threats which many anonymous callers used as a popular prank following the attack on the Awami League leader.

Threats like these naturally created panic and hampered normal activities of these institutions.

A number of gangs are operating in the city whose specialty is in extorting prominent figures.

Targeted wealthy people often get phones where the callers introduce themselves as top-terrorists like 'Picchi' Hannan, Kala Jahangir or Subroto Bain.

They then demand tolls ranging from Tk 50,000 to even three lakh or higher or warn of dire consequences.

The police regularly receive complaints of threatening phone calls but find it hard to determine whether they are hoaxes or from genuine criminals.

"We give our utmost effort in such cases, but the problem occurs in the cases of calls from cell phones," said the duty-officer of Tejgaon police station adding that it is easier to hide numbers in certain cell phone sets.

"When the caller's number on a mobile phone is displayed as 'unknown' or 'not available', it is presumed that the call is from either an NWD(nation-wide dialing) or an ISD (International standard dialing) phone," said a customer service personnel of a reputed mobile phone operator.

Calls can be traced only when written police notice or other such documentation has been provided to the legal department of the cell phone operator.

"The caller ID system is available with the new phone lines that are being provided," said Mukhlesur Rahman, director maintenance & operation, BTTB.

Earlier this year the BTTB had announced that it will upgrade and expand networks and thus interconnect fixed phone operators and calling line identification presentation (CLIP) through an investment of around Tk 30 crore by the end of 2004.

Old exchanges would not receive the installation of such systems due to equipment and software which can no longer be upgraded.

"The introduction of caller ID in the existing systems is extremely necessary for nabbing such extortionist gangs, teasers and criminals in general quickly," said Ashraful Huda, commissioner of Dhaka Metropolitan Police.