The boss of BT has warned it would be "impossible" to strip Huawei products out of the UK's telecommunications network within the next decade.
He also warned of "outages" and possible security risks if the sector was told to curtail all business with the Chinese technology giant during the building of the 5G network upgrade.
It follows suggestions a decision is due to be made public by UK culture secretary Oliver Dowden over the future of Huawei in the UK.
Mr Dowden, speaking last week, said US sanctions on Huawei were likely to have a "significant impact" on the firm's ability to play a role in the UK's 5G network.
Speaking since, Cabinet Office minister Michael Gove said a decision on Huawei would be made by the National Security Council (NSC) and announced to Parliament.
Philip Jansen, chief executive of BT, told BBC Radio 4's 'Today' programme: "Huawei has been in the telecoms infrastructure for about 20 years and is a big supplier to BT and many others in the UK telecoms industry.
"It is all about timing and balance. So if you want to have no Huawei in the whole of the telecoms infrastructure across the whole of the UK, I think that's impossible to do in under 10 years."
The industry would want to be given a seven-year window to rip out Huawei from the 5G network but Mr Jansen said "we could probably do it in five".
He warned there would be consequences as a result of rejecting business with the firm.
"We always, at BT and in our discussions with GCHQ, take the view security is paramount. It is our number-one priority," he said. "But we need to make sure that any change of direction doesn't lead to more risk in the short-term - I think that's where the detail really matters.
He said there was a danger that "accelerating the rip-out" of Huawei from the 5G network meant that effort was not being put into extending the service provision across the country.