More than 110,000 consumers could lose their pay television service unless NTL and Chorus can prevent the introduction of new global telecoms regulations.
The rules threaten to transfer the radio spectrum band used by the cable operators to the owners of third (3G) generation mobile licences from 1st January 2008.
NTL and Chorus are both lobbying the Commission for Communication Regulation (ComReg) to try to prevent the transfer of the spectrum. However, the mobile companies are arguing that use of the spectrum should be made solely available for 3G services - typically video clips and fast internet access.
The new rules are being introduced by the European Conference of Postal and Telecommunications Administrations (Cept) - in an attempt to harmonise the use of radio spectra in Europe.
If implemented, it will mean the two cable firms NTL and Chorus will have to give up the 2.6 gigaHertz spectrum band which they currently use to provide wireless MMDS TV service.
This would affect up to 90,000 Chorus customers and 20,000 NTL customers who currently receive their multi-channel television through a wireless system.
In a recent submission to ComReg, NTL says it is "deeply concerned" that the regulator has not yet adequately recognised the legal problems relating to the implementation of the Cept decision in the Republic. The firm says there is no legal basis for the transfer of the use of the radio spectrum to 3G operators and its own MMDS licence - which runs until 2012 - should take precedence over the Cept decision.
But in its submission, Vodafone, the only firm in the Republic to launch commercial 3G services, says that international standards are necessary to ensure equipment standardisation and roaming for 3G services.