India's cellular service firms said on Friday they had approached a telecoms court to resolve an interconnect row with rival fixed-line phone operators providing cheaper limited mobility services.

Last week, the $5.0-billion mobile services sector had refused to implement an order from the telecoms regulator to offer interconnect facilities to limited mobility operators, saying access charges were discriminatory and hurt its business.

Several mobile operators have barred limited mobility calls originating from fixed-line networks, prompting a Telecom Regulatory Authority of India notice that sought an explanation and warned of punitive action.

"The industry was today compelled to take the matter to the Telecom Disputes Tribunal to ask just redressal," the Cellular Operators Association of India said in a statement.

The spat could stall the nationwide rollout of a limited radius service by the Reliance group, India's largest private conglomerate by sales, which began on Wednesday.

Mobile customers pay Rs 1.20 as an access charge each time they make a call to a fixed-line phone or a limited radius mobile phone. But fixed-line phone users that make a call to a cellular phone do not pay this charge.

The loss-making cellular industry says the TRAI should either ask fixed-line firms to pay a similar charge or exempt mobile firms from the levy.

Fixed-line phone firms "should not be given preferential treatment", the statement said.

Cellular firms have been battling TRAI and basic operators providing the wireless in local loop mobility service, which works on code division multiple access technology, saying it provides basic operators an edge in winning users in the sector.

India's nine-year-old mobile sector, which has more than 10.5 million users, is billed as one of the fastest-growing markets globally as penetration levels are much lower than near saturated mobile markets in most nations.

The main players in the cellular market are Bharti Tele-Ventures Ltd, 16 per cent owned by Singapore Telecommunications Ltd; the Indian mobile unit of the Hutchison Whampoa conglomerate; and Idea Cellular Ltd, partly owned by Indi's Tata and Birla groups along with US firm AT&T Wireless Services Inc.

Cellular operators say they have received "threats of disconnection" from state-run, fixed-line phone companies Bharat Sanchar Nigam Ltd and Mahanagar Telephone Nigam Ltd, which also provide limited mobile services.

The warnings by BSNL and MTNL, India's main telephone companies, would mean private cellular users would be denied access to 40 million fixed-line subscribers and to over a million MTNL and BSNL cellular users.