Australia’s biggest telecommunications companies warned on Tuesday afternoon that customers are likely to face another round of mobile plan price increases after the government set a bill of more than $7.3 billion for access to the radio spectrum used for phone calls.

The warning came fast. The Australian Communications and Media Authority told Telstra, Optus, TPG Telecom and NBN Co it would shave just $20 million off the proposed cost of renewing their spectrum licences, leaving the sector facing a charge that operators said leaves them with no choice but to push prices higher.

The spectrum licences cover the radio waves that carry mobile phone calls, making them a basic cost of doing business for the industry. The Australian Communications and Media Authority, which regulates the telco sector, delivered its decision after the companies faced intense industry pressure and threats of legal retaliation over the pricing proposal.

For customers, the timing matters because the warning came immediately after the government announcement, turning what had been a regulatory fee dispute into a likely hit to monthly phone bills. The major operators have not said how much more expensive plans could become, but the message from the sector was blunt: the extra cost will be passed on.

The tension now sits between the government’s drive to secure more than $7.3 billion from spectrum access and the telcos’ argument that the price leaves them no room to absorb the cost. With only $20 million shaved from the proposal, the dispute has moved beyond negotiation and into a fight over who will ultimately pay for the airwaves that keep Australia’s mobile networks running.