The communications services companies of the two Ambani brothers on Monday announced agreements for trading and sharing of scarce airwaves, or radio frequency spectrum, in the 800 MHz band, covering virtually the entire country.

A roaming agreement is also on cards.

The pact for trading involves a change in spectrum allotment from the Anil Ambani-led Reliance Communications to Mukesh Ambani-led Reliance Jio over nine circles and that for sharing between the two companies covers 17 circles, the two entities said.

"The spectrum arrangements between Reliance Jio Infocom and Reliance Communications will result in network synergies, enhanced network capacity and will optimise spectrum utilisation and capex (capital expenditure) efficiencies," the companies said in separate statements.

"Both operators anticipate considerable savings in operating costs and future investment in networks."