Security agencies have raised an alarm over the non-compliance by telecom operators in blocking or intercepting calls on mobile phones without International Mobile Equipment Identity (IMEI) number.

The security agencies had approached the Department of Telecom last year for strict compliance of its order for not allowing mobile phones without IMEI numbers or with IMEI having all zeros.

According to data compiled by Telecom Enforcement Resource and Monitoring (TERM) security cell of the Telecom Department, the performance of most of the service providers are "unsatisfactory" in following IMEI-related instructions.

The security agencies use the IMEI code for interception and without this number, it becomes difficult to analyse the intercepted target.

A random check was done in states and Union Territories of Andaman and Nicobar Island, Hyderabad, Assam, Bihar, Chhattisgarh, Haryana, Jammu and Kashmir, Kerala, Madhya Pradesh, Rajasthan, Maharashtra, Uttarakhand and Northeast.

The status of compliance of instructions on IMEI provided by TERM cell was "unsatisfactory" and showed "the non-implementation of the instructions of DoT in proper way which has implications on working of law enforcement agencies," the report said.

Taking the case of Assam, the report said that every 10th call was getting Equipment Identity Register (EIR) query.

The EIR database holds records for three types of mobile -- black, grey and white. When a mobile requests services from the network, its IMEI is checked against the EIR to assess which category of the mobile it falls into.

Black mobiles are those reported stolen or whose operation will adversely affect the network. These mobiles will not be allowed to access the network.

Grey mobiles are classed as non-conforming to all the guidelines under which the operators work, but may be used on the network. White mobiles are those that conform to requirements set down by the network operator.

In Madhya Pradesh, while operators had an "unsatisfactory" position on implementation of the IMEI guidelines, it had become "satisfactory" in the audit carried out on June 14, 2010.