The telecom tribunal TDSAT on Wednesday set aside Rs 50 crore penalty imposed by the DoT on Bharti Airtel for allegedly camouflaging calling-line identification (CLI) in MP circle, saying it should have allowed the private operator to present its side of the case.

However, the TDSAT bench headed by its Chairman Justice S B Sinha also said the conduct of Airtel in this entire episode was "not free from of any blemish".

"While the impugned demand cannot be upheld on the ground stated herein before, there cannot be any doubt that the conduct of the Bharti Airtel is not free from any blemish," said TDSAT while asking DoT to refund Airtel's Rs 50 crore without any interest.

If DoT does not return the amount within four weeks then it would have to pay 12 per cent interest, the tribunal said.

TDSAT said it was "of the opinion that it would be necessary that the Airtel is given an opportunity of hearing by the DoT".

Airtel has set up a call centre in Indore for making business promotion calls to non-Airtel mobile customers during implementation of Mobile Number Portability (MNP).

"However, when the said calls were generated, the record of the called party was showing its own number instead and in place of party A i.e. calling party number, the one of the called party (B party) was showing", the order paper said.

A complaint was made by a customer to BSNL, who in turn forwarded the same to Department of Telecom on January 2011.

DoT on the same date asked Airtel to provide Call Detail Records (CDRs) January 16-18, 2011 for all trunks with BSNL as well as for providing Home Location Register (HLR) Dump.

Following that DoT wrote a letter to Airtel asking why action should not be taken against it, saying calling line identification (CLI) was found camouflaged in more than 8000 calls and it was a violation of License agreement.

Telecom Enforcement, Resource and Monitoring (TERM) Cell, DoT's vigilance wing, also visited Airtel's premise at Indore and Delhi for inspection.