Rajasthan network troubles: Tejas signals cooperation with Airtel, BSNL

The announcement follows the department of telecommunications (DoT), through its wireless planning and coordination (WPC) wing, taking charge of the Airtel-BSNL signal interference matter, with officials saying the issue is under active supervision and moving toward a workable technical solution.

“The interference observed at a few Airtel sites in the Rajasthan circle is in no way a reflection of the quality or capability of its equipment. The solution is to perform additional filtering on the antennas and does not require any change to our equipment," Arnob Roy, executive director and chief operating officer at Tejas Networks, said in response to Mint’s queries.

“BSNL is in the process of deploying additional filters for this purpose and has already implemented them at approximately 1,000 sites," he added.

Notably, BSNL has also approached telecommunications minister Jyotiraditya Scindia to get his guidance on the issue, and a review meeting on the matter is expected soon, said a government official on the condition of anonymity.

Queries emailed to BSNL and the DoT remained unanswered until publication.

The conflict

Airtel raised the issue of network interference with BSNL in the Rajasthan circle to Tejas Networks a few weeks ago, as it had been facing service quality issues since December 2024, and the telecom equipment maker had taken no corrective action.

Tejas has deployed the equipment for BSNL’s 4G rollout. Airtel said that in the Rajasthan circle, the deployment in the 800MHz band was interfering with its 900MHz band, thereby affecting quality of services for consumers.

“Radio equipment made by all global vendors for India for the 850MHz band conforms to Indian frequency allocation requirements, which means the signal from the 850MHz band gets turned off within a certain limit and thus does not interfere with the uplink of the 900MHz band. But the radio equipment made by Tejas for the 850MHz for India—being used by BSNL—radiates signals beyond those limits, thus interfering with Airtel’s 900MHz uplink," a Bharti Airtel spokesperson said in a statement over email.

“To resolve the matter, Tejas needs to use a filter to ensure the equipment radiates signals only up to the limit," the Airtel spokesperson added. The tensions between Airtel and Tejas Networks increased when the former called the latter’s equipment “sub-standard".

“Since our equipment is co-existing with other operators’ equipment in all states across 100,000 sites, without any interference issues, it can obviously not be sub-standard in only one band in one state," Roy said, adding that the problem could be due to closeness of tower sites as well and therefore it is essential to implement additional filtering on the antennas to mitigate adjacent channel interference.

The filtering is required when two base stations operating in adjacent bands are located in close proximity at neighbouring sites, with antennas facing each other. “This situation is much more severe than the case when base stations are deployed on the same tower, since the antennas are not facing each other," Roy explained.

Airtel, however, said towers have historically accommodated two or more sites of different operators without interference, so the problem is not due to the closeness of sites.

In the Rajasthan circle, the adjusted gross revenue (AGR) of Airtel rose 19.7% year-on-year to ₹3,337 crore in the first half of 2025-26, according to a 25 November report by ICICI Securities. Rajasthan accounts for around 6.1% of Bharti Airtel’s AGR of ₹54,767.8 crore in the first half, according to the report.

"As India’s 800MHz band sits dangerously close to the GSM 900 band, it leaves almost no guard space between BSNL’s downlink and Airtel’s uplink, which is the root cause. Also, when base stations are located very close to each other, interference becomes inevitable. The only realistic solutions are to increase physical separation between sites or add additional high-grade filtering at the antenna to suppress spill-over," said Parag Kar, an independent telecom analyst.

Regulatory gap

In its recent submission to the Telecom Regulatory Authority of India (Trai) on the spectrum auction, Airtel said the Indian regulatory framework lacks explicit, comprehensive guidelines to address interference mitigation in scenarios involving adjacent-band deployments.

“To date, only limited, case-specific field trials have been conducted, which are insufficient to standardize interference management nationwide," Airtel told Trai earlier in November.

On 19 November, Mint reported that BSNL has flagged weak transmission signals to its vendors Tata Consultancy Services (TCS) and Tejas at thousands of its new 4G towers—an issue behind call drops and slower data speeds. The state-owned telecom operator had called the vendors to investigate and fix the problem.

In response to Mint’s queries, TCS and Tejas said most of such issues have been fixed and there is no impact on the company’s key performance indicators (KPIs).

The companies said call quality KPIs, including drops, are well within acceptable limits and on par with other networks. They added that network optimization to reduce call drops and improve coverage is an ongoing process for any mobile network, and there are no issues of coverage or throughput in the vast majority of the over 94,000 operational sites of BSNL.

BSNL’s indigenous stack was developed by Tejas Networks and C-DOT, with TCS serving as system integrator. In 2022, as part of a revival package cleared by the Union cabinet, the government had approved 100,000 4G tower sites for BSNL at a cost of ₹19,592 crore. BSNL spent ₹25,000 crore in 2024-25 to install these towers for 4G services. TCS and a C-DoT-led consortium had bagged the lion’s share of the ₹25,000-crore project to supply telecom gear to BSNL.