Broadband provider Orange is unsure of delivering on the government's Digital Britain plan due to technical limitations.
The group has said that unless Vodafone and O2 share part of the 900Mhz spectrum which they occupy, Orange will not be able to complete its contribution to the programme.
At present, O2 and Vodafone have exclusive rights to the 900Mhz band, which has led Orange and other providers to pressure the telecoms regulator Ofcom.
Steve Blythe, Orange UK Head of Spectrum Strategy, told Mobile News: "The lower the frequency, the further it travels and the broader area it covers, with fewer base stations.
"So Vodafone and O2 can expand their networks into rural areas at a lower cost; Orange can't."
Meanwhile, an expert from the supplier Quintain Estates has suggested that residential areas in the UK are not yet equipped to deal with ultra-fast broadband speeds of up to 100Mb.